Forensic linguistics: A scientometric review

Abstract Forensic linguistics is a distinct field of study in the science of language that places significant emphasis on the observation of language usage in our daily lives, including spoken and written language, listening, and reading. This focus on language usage provides a legal perspective for the analysis of language. Initially, forensic linguistics was confined to the identification of spoken and written documents in legal settings, police language, and prison language; however, the field has expanded to include speech detection, text detection, plagiarism detection, social media verbal violence detection, social security detection, and discrimination detection. In this study, we examined the development of forensic linguistics through the use of knowledge maps. We conducted a scientometric analysis of 6,490 triangulated documents from three major knowledge databases (Scopus, WOS, and Lens) that were published between 1936 and 2022. The development of forensic linguistics was measured using eight bibliometric indicators and eight scientometric indicators, and we used CiteSpace 5.8.R3 and VOSviewer 1.6.18 software packages to create knowledge maps and tabulations. Our major findings include the identification of commonly used keywords in forensic linguistics, such as human, linguistics, legal translation, language, speech recognition, legal language, authorship attribution, and natural language processing system. Additionally, the following terms were observed to be synonymous with forensic linguistics: linguistic law, language policy, language and law, official language, legal translation, linguistic rights, and legal linguistics. Our scientometric analysis allowed us to group the 6,460 documents in forensic linguistics into various clusters based on research patterns in the field, such as the role of forensic linguists in legal contexts, legal translation, legal composition, forensic voice comparison, authorship attribution, and human language technologies. Other clusters included the use of forensic linguistics in police interview settings, public service and courtroom settings, linguistic rights, as well as online debate. The study has implications for researchers, writers, public speakers, YouTubers, and all social media users, TV reporters, news reporters, and media professionals. In contemporary society, there is a rapid proliferation of ignorance concerning copyrights and the rights of others. Therefore, it is crucial to raise awareness among the general public about these rights.


The rise of forensic linguistics
Language is an essential part in every aspect of human life, entailing a deeper linguistic understanding as applied to a multitude of other disciplines deemed essential not only for linguists but also for a wide range of specialists, including lawyers (Udina, 2017).Of the vivid well-known integrative developments of modern scientific study of language signaling the primary importance of the interconnection of linguistics and other disciplines, including law (P.Tiersma, 2008), is the emergence of forensic linguistics, also known more generally as legal linguistics or language and the law (McMenamin, 2002).Drawing conclusions form the Oxford English Dictionary definition of the word "forensic" as: an adjective "pertaining to, connected with or used in courts of law", it becomes clear that law is codified in language (Ali, 2020, p. 41) and that forensic linguistics, as a discipline, has significantly contributed to criminal justice system (Houtman & Suryati, 2018) through disclosure of truth of legal cases by means of linguistic data analysis (Shuy, 1996) and is the interface between language, crime and law (Khoyi & Behnam, 2014).The rise of forensic linguistics as a recent, rapidly growing area of modern applied linguistics is deeply rooted in the close interdependence between language and law which has attracted the keen interest of philosophers, linguists and specialists for long, with a history extending over as far as 2400 years old (McMenamin, 2002), all the way down under Latin, Anglo-Saxon, Norman, French influences up to the twentieth century (Tiersma, 1999).Forensic linguistics, as a term, has had no actual recognition until the year 1968 when Professor Jan Svartvik introduced the term in his book The Evans Statements: A Case for Forensic Linguistics (Ariani et al., 2014), even though the term Forensic English was used by Philbrick (1949) in his book title on legal English, Language and the Law: the Semantics of Forensic English but the phrase was not taken up (Coulthard & Johnson, 2007).
The birth of forensic linguistics as a branch of modern applied linguistics firmly grounded on close, evident interdependence and relationship between language and law (Udina, 2017) has a relatively long controversial history (Hunyadi, 2003) surrounded by uncertainty among scholars, since the eighteenth century, over authorship issues of famous texts, sacred books and Shakespeare's plays (Olsson & Luchjenbroers, 2014).The advent of writing induced the production of written legal and religious codes and hence the field of language and law was born (Butters, 2011b), igniting increased interest among scholars in various non-legal fields to use linguistic expertise in solving legal issues including, for example, speaker or writer identification and person's rationality among other factors (Tiersma & Curtis, 2008).
The foundations of forensic linguistics can be traced back to the period of early significant work on language and the law, starting with (Bryant, 1930) compendium on function words in legal language, followed by Wetter (1960) on style of written appellate decisions in legal context (as cited in McMenamin, 2002).The most important development in the language of the law was initiated by (Melinkoff, 1963) The Language of the Law.In this book, the author began his influential clear, brief language campaign carried on by the author and others through the next three decades.It was not until the year 1968 where the earliest attested usage of the term "forensic linguistics" was introduced with the publication of (Svarvik's, 1968) The Evan Statements: A Case for Forensic Linguistics, providing an analysis of four statements purportedly made to the police by Timothy Evans in which he confessed to strangling his wife and baby daughter in 1949 (Blackwell, 2012), marking the birth of a new area of forensic expertise (Coulthard & Johnson, 2007).
Initially, the growth of forensic linguistics was slow, involving just isolated articles where distinguished linguists analyzed legal criminal-related documents and commented on their likely authenticity (Coulthard & Johnson, 2007).This period in the development of forensic linguistics extending up to the late 1980s was characterized by diversity of disciplines, scarcity of research limited to articles or book chapters and a lack of institutionalized forensic linguistics, too early to regard it as an academic discipline or a methodology, where "the work was undertaken as an intellectual challenge and almost required the creation, rather than the application, of a method of analysis" (Coulthard, 1995, p. 1).
The early 1990s marks the maturity of forensic linguistics as a distinct multi and crossinterdisciplinary field in its development stage, all the way down to the third millennium, with a series of early gatherings and seminars, culminating in the establishment of the International Association of Forensic Linguists (IAFL) (IAFLL, n.d.), the International Association for Forensic Phonetics (IAFPA) (IAFPA, n.d.), and the journal Forensic Linguistics: The International Journal of Speech, Language and the Law (IJSLL) (IJSLL, n.d.) (Blackwell, published by Routledge, to serve as the official organ of both the IAFP and the IAFL playing "a pivotal role in further developing, refining and testing . . .methodologies, in disseminating the results of research and in making available experience from case studies" (French & Coulthard, 2013, p. viii).Forensic linguistics, during this period, was enriched with bigger, up-to-date research proportions form a wide range of disciplines including linguistics, law, psychology, anthropology and sociology, under diverse topics like handwriting analysis, forensic phonetics, linguist expert role in court, covering work in US, UK, Australia, Europe, North America and Germany among other countries (Coulthard & Johnson, 2007).Except for O' Barr (1982), the period from the 1990s onward witnessed the production of more book-length studies with the word "forensic" in their title, by many proponents of the field in key areas, such as forensic phonetics (Baldwin & French, 1990;Rose, 2002), forensic stylistics and author identification (McMenamin, 1993;McMenamin, 2002), forensic linguistics (Gibbons, 2003;Olsson, 2008), legal language (Solan & Tiersma, 2005), courtroom interaction (Archer, 2005;Matosian, 1993), language and power (Cotterill, 2003) and the linguist as expert in court (Shuy, 2006;Berk-Seligson, 2002), police, law enforcement and interrogation language (Shuy, 2005), psychological (Gudjonsson, 2002a) and conversational analytic (Heydon, 2005) perspective (Heydon, 2005).
In the course of its rapid development towards the close of the twentieth century and the beginning of the third millennium, forensic linguistics has taken a more well-organized active presence, with a more developing methodology and a growing number of linguists as experts (Coulthard & Johnson, 2007) owing to a series of seminars taking place in various countries, giving birth to the International Association of Forensic Linguists (IAFL) in 1993, the International Association for Forensic Phonetics (IAFP) in 1991, and the Journal Forensic Linguistics in 1994, later renamed as The International Journal of Speech, Language and the Law in 2003 (P.French & Coulthard, 2013).Of the earliest organized gatherings on forensic linguistics held in Germany were a two-day conference in FL by Bundeskriminalamt (BKA, Federal Criminal Police Office) in 1988, a number of conferences at Mannheim University organized by the late Lothar Michel on forensic handwriting analysis in 1989, and sessions on forensic linguistics held by the German Applied Linguistics Association (GAL) 1990 to 1992, stirring a significant pioneering interest that influenced forensic speaker identification practices in several EU countries including Germany, Austria, Sweden, the Netherlands, and Spain (Broeders, 2001).
In the UK, seminars on forensic linguistics took place at the University of Birmingham on the initiative of Malcolm Coulthard in 1992 with a growing number of linguists and lawyers from several countries including Brazil, Australia, Germany, Greece, Ireland, the Netherlands, and Ukraine, consolidating a consensus for the need of an international association (Blackwell, 2012), culminating in the most remarkable advance in the study of forensic linguistics in 1994 with the Birmingham University launch of Forensic Linguistics: The International Journal of Speech, Language and the Law, with Malcolm Coulthard and Peter French as editors, and the founding of the International Association of Forensic Linguistics (IAFL) (McMenamin, 2002).
The years following the founding of the IAFL, forensic linguistics internationality became visible on several academic conferences which took place in Bonn, Germany in 1993, Amsterdam in 1993 chaired by Professor Hannes Kniffka, in Australia in 1995 and the USA in 1997.The 4th IAFL Conference in 1999, unlike the previous ones, was larger and constituted a turning point in which the IAFL Web site was created by Jess Shapero (http://www.iafl.org), a pioneering effort, enabling potential participants around the world to remain informed about changes to the program without having to rely on the postal system (Blackwell, 2012).Moreover, first MA course in forensic linguistics introduced at Cardiff University in 1999 and the Centre for Forensic Linguistics was established at Birmingham's Aston University to cope with the increasing demand for forensic linguistic skills in 2008 (Gao, 2010).
The growth of forensic linguistics continued steadily towards the end of the twentieth century, with the provision of forensic linguistics courses and study modules taught at undergraduate and postgraduate programs at emerging universities in the USA, England, Wales, Australia, China, Hong Kong, Finland, Germany, Japan, and South Africa (Blackwell, 2012).From the year 2000 onwards, there has been a marked shift away from the Anglo-centric, common-law bias dominating the field of forensic linguistics in the previous decade; the IAFL biennial conferences subsequently were no longer the only means to the exchange of ideas in the field, initiating several gatherings such as Łódz event in 2005, followed by the 2 nd IAFL European Conference on Forensic Linguistics/Language and the Law in Barcelona in 2006, and by annual conferences at Adam Mickiewicz University, Poznan from 2006, all the way down to 2008 with the launch of the Centre for Forensic Linguistics at Aston University, which has hosted the FL Summer School, now an annual event, since 2006 and where Malcolm Coulthard now holds the world's first professorial chair in forensic linguistics (Blackwell, 2012).This period in the development of forensic linguistics is characterized by bringing new challenges to the discipline owing to new speech and text technologies as opposed to traditional means (Hunyadi, 2003), firmly asserting that forensic linguistics, as a new branch of applied linguistics, is at the center of two parallel increasing trends both aiming at: utilizing technology to assist in the analysis of text and (ii) scrutinizing digital data through the lens of traditional linguistic and discursive analytical methods of speech (MacLeod & Wright, 2020).
Forensic linguistics is now largely recognized as its own distinct field; it has spread around the world, broadening in scope and becoming recognized and utilized in a variety of jurisdictions and contexts (Perkins, 2021).Today forensic linguistics is a widely recognized field.The International Association of Forensic Linguists "aims to bring together those working on any aspects of language and the law" (http://www.iafl.org/)and works to promote research into the practice, improvement, and ethics of expert testimony and the presentation of linguistic evidence, as well as legal interpreting and translation" and is working to create a standard for forensic linguistic experts.The key journal in this area is The International Journal of Speech, Language and the Law formerly titled Forensic Linguistics (Perkins & Grant, 2013).

The scope of forensic linguistics
Seen as an academic sub-branch of applied linguistics, in theory, and a practical branch of forensic science, in application to legal contexts, (Jordan, 2002), forensic linguistics by nature is a linguistically-oriented science concerned with intersections between language and legal field (Correa, 2013).Broadly defined, better known as "language and law", forensic linguistics is an application of linguistic theory and method to any point at which there is an interface between language and the law (MacLeod & Wright, 2020, p. 360), language analysis and study as applied to legal settings (Kniffka, 2007) the study of courtroom discourse (Tiersma, 1999), legal interpretation and translation (Berk-Seligson, 1990), the readability/comprehensibility of legal documents and jury instructions (Tiersma & Curtis, 2008), police caution comprehensibility to suspects (Cotterill, 2000), linguistic minorities in the legal process (Eades, 1994), children in the legal process (Morrisett et al., 1999), and numerous other areas where language and law interact with each other (Blackwell, 2012).The narrow definition of forensic linguistics implies the application of linguistic methods to the production of expert evidence, concerning for example disputed confessions, trademark disputes, threats and attempts at extortion, taped conversations in which individuals allegedly offer bribes (Shuy, 2005), suicide notes (Shapero, 2011), and disputed authorship and alleged plagiarism (Kniffka, 2000).Having its origin in applied linguistics, forensic linguistics is particularly concerned with the professional and institutional interaction in legal contexts (Coulthard et al., 2017a), where language texts are studied, analyzed and measured in both spoken and written forms (Umiyati, 2020).
Forensic linguistics is truly inter-and cross-disciplinary in composition, overlapping with several disciplines such as communication, criminology, law, linguistics, sociology, and translation studies (Johnson & Coulthard, 2010).The scope of forensic linguistics is difficult to define as it covers aspects of language from the level of phonetics to discourse analysis in the stages of investigation, trial and interpretation.However, the areas covered under forensic linguistics, based on (McMenamin, 2002) and (Umiyati, 2020) are listed, not exhaustively, as follows: • Handwriting and signature identification.
• Phonetics and phonology both auditory and acoustic.
• Semantics (interpretation of expressed meaning) • Discourse and pragmatics (interpretation of inferred meaning The three key elements of forensic linguistics as a distinct discipline comprise the following : (i) the (written) language of the law, (ii) the language of (spoken) legal processes, and (iii) language analysis as evidence or as an investigative tool (MacLeod & Wright, 2020), serving as the interface between language and law where legal remedies are sought (Olsson, 2009).Within the area of investigative language and evidence provision, forensic linguists perform various tasks in the scope of comparative authorship analysis, sociolinguistic profiling, interactional meaning, determining meaning, and trademark disputes and copyright infringement (Perkins, 2021).Forensic linguists' core business is to examine documents of anonymous or disguised origin, such as bomb threats, ransom or suicide notes, or other messages associated with crime (Jordan, 2002) to determine their authentic authorship or decide if the documents have been altered or tampered with in any way (Varney, 1997), including new emerging technological forms of texts such as phone SMS messages, tweets and forums (Bhatia & Ritchie, 2012).While forensic linguists can only give professional opinion on authorship authenticity of documents or recordings under question and not on the psychology or social setting of suspects without police help (Blackwell, 2012), utilizing forensic linguistic awareness among lawyers and police officers contributes to a better delivery of justice, emphasizing that forensic linguistics is a collaborative work of interrelated fields in investigative settings (Perkins, 2021).
Technological developments have contributed to the emergence of technological media in the forensic-linguistic process (Surahman, 2021) in the best interest of both investigators and forensic linguists in collecting data and working accurately on language evidence phonetic or textual forms, opening new directions for research contributions in digital computing and using large corpora for relevant data and relevant population (MacLeod & Wright, 2020).In seeking clues for authorship in language evidence, the forensic phonetics methods are fairly sophisticated, incorporating technological equipment to give accurate outcomes in terms of speaker voice identification, comparing anonymous messages with the known features of various language varieties (Jordan, 2002).Voiceprint analysis is one such method used widely in legal cases including blackmail, kidnapping, confessions, telephone bomb threats, conspiracy, where the unique acoustic features of voice for every single human are detected using sensitive equipment, showing the base features of the original voice even under disguise (Varney, 1997).
It can be inferred that the intersections between forensic linguistics and other areas of applied linguistics (mainly sociolinguistics, pragmatics, and discourse analysis) in three interrelated areas: linguistic evidence, language and the law, and language during legal procedures and courtroom discourse has shown the immense contribution of applied linguistics in the codification of law, delivery of justice and maintenance of the rights of linguistically vulnerable populations (Correa, 2013).Forensic linguistics, which encompasses audio and digital forensics, has made significant contributions to various institutions, including digital humanities, as well as relevant parties such as prosecutors and law enforcement agencies.Its purpose is to analyze and determine the validity of language-based evidence, such as speech, in legal contexts (Surahman, 2021).Potential of linguistic understanding coupled with collaboration across the areas where language and law intersect will enhance the importance and utility of forensic linguistics in delivering justice and linguistic facilitation training for investigators (Perkins, 2021).However, all such unprecedented developments in the field of forensic linguistics are accompanied with several limitations that should not be ignored.One of the limitations is that linguistic evidence alone is not sufficient to convict or exonerate a person.In addition, it should be noted that linguistic analysis facilitated by technology is not always entirely reliable and can be subject to interpretation.Moreover, the inability to conduct experiments in the courtroom can make it challenging to demonstrate what actually occurs in such settings (Correa, 2013).

Scientific contributions for forensic linguistics
The growing efforts in the 1990s in the development and institutionalization of forensic linguistics as a discipline culminated in the establishment of its own professional International Association of Forensic Linguists (IAFL) founded in 1993 (Johnson & Coulthard, 2010) International Association for Forensic Phonetics (IAFP), and the launch of the journal Forensic Linguistics: The International Journal of Speech, Language and the Law founded in 1994, a peer-reviewed journal published by Routledge with articles on any aspect of forensic language, speech and audio analysis (Blackwell, 2012).
Since its beginning in 1994 as Forensic Linguistics: The International Journal of Speech, Language and the Law, the journal changed to its present title The International Journal of Speech, Language and the Law in 2003 now online at (https://www.iafl.org/journal/) to reflect a broadening of academic coverage and readership and to serve as the official organ of both the International Association of Forensic Phonetics IAFP and the International Association of Forensic Linguists IAFL (IAFP, n.d. Blackwell, 2012;IJSLL, n.d. Linguistics. IAFL, n.d.).The journal plays "a pivotal role in further developing, refining and testing . . .methodologies, in disseminating the results of research and in making available experience from case studies" and is "intended to appeal to readers and contributors from a number of different sub-disciplines of linguistics, as well as to solicitors, barristers and judges who have little or no prior knowledge of the concepts and terminology connected with linguistic study" (French & Coulthard, 2013, p. viii).Currently published by Equinox in the UK, the journal has published 28 biannual issues and continues to be the topmost official journal of the International Association of Forensic Linguists and the International Association of Forensic Phonetics and Acoustics, projecting the emerging debate within the forensic linguistics community regarding the scope of the discipline as it evolves and defines itself (Blackwell, 2012).
The International Association for Forensic and Legal Linguistics, currently online at (https://www.iafl.org/about-iafl/), is an organization that comprises linguists as well as legal practitioners with work in the law, more specifically linguistic evidence in court including authorship attribution, disputed confessions, among others (The International Association for Forensic and Legal Linguistics, n.d..).Founded in 1992, at the University of Birmingham, UK, the IAFL aims, through its annual conferences and newsletters, to offer a platform for exchanging ideas and information on forensic applications of linguistic analysis and to improve the administration of the legal systems worldwide by means of a better understanding of the interaction between the language and the law (French & Coulthard, 2013).The creation of the IAFL Web site (now at www.iafl.org) in 1999 which continues to provide resources for members including an online searchable bibliography of research in language and law remains one of the most remarkable contributions of the association to keep participants informed and updated with the latest in research in the discipline (Blackwell, 2012).
The International Association for Forensic Phonetics and Acoustics (IAFPA), now at (http://www.iafpa.net/), is the professional association for forensic scientists and researchers working on voices, speech and audio recordings analysis.IAFPA was formally established in York, England, in 1991 with the name The International Association for Forensic Phonetics (IAFP).The dynamic growth of the IAFP into 120 members worldwide, with expertise spanning both forensic phonetics and acoustics has resulted in the addition of the latter "A" to IAFPA.Initially, the IAFP served as the professional body for phoneticians engaged in forensic work (P.French & Coulthard, 2013).The association aims to encourage research and provide a platform for the interchange of ideas and information on practice, development and research in forensic phonetics and acoustics.The IAFP, through its professional Conduct Committee, has set down and formulated a Code of Practice by which all members are bound.

Purpose of the present study
As mentioned above, forensic linguistics, usually viewed as a field of applied linguistics (Butters, 2011a), focusing on language and law, language in legal processes, language as evidence, and in research and teaching settings (The International Association for Forensic and Legal Linguistics, n. d..).There have been several studies and reviews examining text examination in police documents and reports (Totty et al., 1987), cumulative sum method in for authors determination in police settings (Hardcastle, 1993), author attribution (Kotzé, 2010), cybercrime investigations (R. C. Perkins, 2021), and criminal and civil law settings (Varney, 1997).It has been suggested that forensic linguists can contribute to four main areas, namely, handwriting, phonetics and phonology, discourse analysis, and translation (Varney, 1997).An expanded list was listed by Perkins and Grant, which included written legal language, spoken legal language, comparative authorship analysis, sociolinguistic profiling, interactional meanings, trademark disputes and copyright infringement (R. Perkins & Grant, 2013).Furthermore, forensic linguistics has broad applications in the fields of humanities and computing, including the identification of digital forgery in audio and video recordings (Hunyadi, 2003).Considering authority, Hutton stressed the importance of forensic linguists' roles, and insisted that forensic linguistics must distance itself from core linguistics in order to perform more effective roles in language and law (Hutton, 2005).Despite the fact that forensic linguistics appears to be an older field of study in countries like the United Kingdom and the United States, it continues to grow in other countries (e.g., China, Africa) (Gao, 2010;Mollema, 2019).
A number of recent studies have examined the key elements of forensic linguistics, focusing on the explored and examined areas within this field (e.g., plagiarism detection) (Ariani et al., 2014).An additional study reviewed educational efforts in the area of forensic linguistics to teach language and law (Udina, 2017).Forensic linguistics is developing in the higher education sector and more courses are being offered in universities, indicating the preparation of a greater number of forensic linguists (Coulthard et al., 2017b).In addition, Umiyati conducted a literature review on forensic linguistics, but this review was primarily based on reviewing books relevant to this field (2020).This review is significant in that it outlines the types of texts and sources used in forensic linguistics settings, as well as the most extensively examined areas in the field (Umiyati, 2020).
In this study, a scientometric approach was employed to investigate the rise and development of forensic linguistics.The investigation entailed an examination of 6,460 triangulated documents from three prominent knowledge databases (Scopus, WOS, and Lens) spanning the period between 1936 and 2022.Three key research objectives were formulated to guide the analysis.Firstly, the study sought to determine the extent of knowledge production in forensic linguistics in relation to variables such as year, region, higher education institution, journal, publisher, research area, author, and cited document.Secondly, the investigation aimed to identify the central and most influential authors in the field.Finally, the study sought to delineate the main areas of research in forensic linguistics.

Research methods
Scientometrics, in its simplest form, can be defined as the "study of artifacts; one examines not science and scholarship but the products of those activities" (Glänzel & Schoepflin, 1994, p. 491).The majority of researchers in this field are interested in researching "the quantitative aspects of the production, dissemination and use of scientific information with the aim of achieving a better understanding of the mechanisms of scientific research as a social activity" (Chellappandi & Vijayakumar, 2018, p. 6).Among researchers, there is a division regarding the effectiveness of scientometric studies in assessing the quality of published research.According to a previous study, it was found that: "the task of determining quality papers is especially difficult in BIS [bibliometrics, informetrics and scientometrics] due to the very heterogeneous origin of the researchers" (Egghe, 1994, p. 390).While the goal of such studies has evolved over the last few decades, the purpose of these studies remains the same, to "reveal characteristics of scientometric phenomena and processes in scientific research for more efficient management of science" (Parkinson, 2011, p. 1).
These studies are guided by scientometric indicators.Indicators may relate to elements (e.g., publications, citations, references, potential, etc.) or types (e.g., quantitative, impact) (Parkinson, 2011)."Mapping knowledge domains" is also a subject that is worthy of mentioning.A critical component of the process is the creation of "an image that shows the development process and the structural relationship of scientific knowledge"-using maps that are "useful tools for tracking the frontiers of science and technology, facilitating knowledge management, and assisting scientific and technological decision-making" (Huang et al., 2021, p. 6201).In a recent study, it was  suggested that this approach could be applied across all fields of study, not just medical, health, and pure sciences (Sooryamoorthy, 2020).The field of forensic linguistics is examined in this present study as an interdisciplinary area of linguistics that integrates with other fields like law, forensic science, sociolinguistics, etc.

Measures
Our previous discussion has already indicated that both bibliometric and scientometric studies are used to guide the assessment of the knowledge produced in a given field (e.g., forensic linguistics).

Data-collection and sample
We retrieved data from Scopus, WOS, and Lens.Several reasons justified the use of these databases.Both Scopus and WOS are not only knowledge databases that entail a wide collection of knowledge based articles, but they also contain a wide range of source materials which are curated based on the quality of the research (Birkle et al., 2020;Burnham, 2006;Pranckutė, 2021).Moreover, it has been pointed out that Lens was more comprehensive than the other two databases, i.e. it had a larger range of data that was not included in the other two databases, thus making Lens a better database overall (Penfold, 2020).
On Wednesday, 22 June 2022, data were retrieved for this study.Language restrictions were not imposed as long as the title, abstract, and keywords were available in English.However, owing to the scarcity of results in other languages, a manual verification process was conducted.The study incorporated all types of documents that met the criterion of containing the full-text.A comprehensive description of the search strings used in the three databases and other relevant specifications can be found in Table 2.
In this study, the concept of "forensic linguistics" and its equivalents were utilized to assess the magnitude and development of research in this field.The search strings employed in our search did not comprise keywords that were exclusively specific to forensic linguistics, such as violent Table 2. Search strings for retrieving data on forensic linguistics from Scopus, WOS, and lens Scopus (ALL ( "forensic linguistics" ) OR ALL ( "legal linguistics" ) OR ALL ( "language and law" )) AND (LIMIT-TO (DOCTYPE, "ar") OR LIMIT-TO (DOCTYPE, "ch") OR LIMIT-TO (DOCTYPE, "cp") OR LIMIT-TO (DOCTYPE, "re") OR LIMIT-TO (DOCTYPE, "bk")) Wednesday, 22 June 2022, 2,780 results document results, 1966-2022 WOS "forensic linguistics" (All Fields) or "legal linguistics" (All Fields) or "language and law" (All Fields) and Articles or Book Chapters or Proceedings Papers or Review Articles or Early Access or Books (Document Types) Wednesday, 22 June 2022, 688 results document results, 1985-2022 Lens (Title: ( AND ("forensic linguistics" AND )) OR (Abstract: ( AND ("forensic linguistics" AND )) OR Full Text: ( AND ("forensic linguistics" AND )))) OR (Keyword: ( AND ("forensic linguistics" AND )) OR ((Title: ( AND ("legal linguistics" AND )) OR (Abstract: ( AND ("legal linguistics" AND )) OR Full Text: ( AND ("legal linguistics" AND )))) OR (Keyword: ( AND ("legal linguistics" AND )) OR ((Title: ( AND ("language and law" AND )) OR (Abstract: ( AND ("language and law" AND )) OR Full Text: ( AND ("language and law" AND )))) OR Keyword: ( AND ("language and law" AND )))))) Filters: Year Published = (1936 -) Stemming = Disabled Publication Type = (journal article, unknown, book chapter, book, dissertation, conference proceedings article, preprint, conference proceedings) Wednesday, 22 June 2022, Scholarly Works (2,992), 1936-2022 language, verbal violence, and document fabrication.Our preliminary Google search and prior familiarity with the field informed the decision to employ the aforementioned search strings to retrieve information related to forensic linguistics (refer to Table 2 for further details).

Data analysis
The data analysis process included several steps before and after.Firstly, Scopus data were exported into three different formats: Excel sheets for bibliometric analysis, CiteSpace RIS files, and VOSviewer CSV files.CiteSpace required the RIS file to be converted to WOS in order to meet its requirements.Data from WOS were also extracted in two formats: text documents were exported in Excel sheets, which could be used for bibliometric analysis, and plain text documents could be used for CiteSpace and VOSviewer.Last but not least, Lens data were retrieved in two formats: CSV for bibliometric analysis and full record CSV for viewing in VOSviewer.
CiteSpace and Mendeley were used to remove duplicates before starting the analysis in CiteSpace.We then used Excel to perform the bibliometric analysis.Citation reports were generated and converted into figures using Excel.
Since no settings were changed in either software package, scientometric analysis settings were set to default.There were three different visualisations created for each database, namely network, overlay, and density.We analysed Scopus and WOS data three times per dataset: cooccurrences by author keywords, co-citations by source, and co-citations by cited authors.In the case of Lens, four analyses were performed: cooccurrence-by-keyword analysis, citation-by-author analysis, citation-by-source analysis, and citation-by-document analysis.Scopus and WOS were each analysed three times in CiteSpace: to identify co-citations by document (references), cocitations by cited authors, and occurrence (keywords).Our analysis resulted in narrative summaries, cluster summaries, maps, and burst tables.

Result overview
The results of this study have been categorized into two sections for the purpose of clarity.The first section presents bibliometric indicators that illustrate the development of forensic linguistics, utilizing data obtained from Scopus, WOS, and Lens databases.The bibliometric indicators include the year of publication, publications by universities, journals, publishers, subjects, and authors whose publications were considered.The second section focuses on the scientometric indicators of forensic linguistics' development, which were analysed using CiteSpace and VOSviewer software.The scientometric analysis included indicators related to citations, co-citations, and cooccurrences.

Overview of Forensic linguistics studies from Scopus, web of science, and lens
For the purpose of analysis, a total of 2,780 papers on forensic linguistics were retrieved from Scopus, 688 from WOS, and 2,992 from Lens databases, spanning the years 1966-2022, 1985-2022, and 1936-2022, respectively.The Scopus database contained 1,523 articles, 224 review articles, 251 conference proceedings (articles), 566 book chapters, and 216 books.The WOS database contained 589 articles, 21 review articles, 82 book chapters, 3 books, 75 proceedings, and 5 early access articles.The documents retrieved from Lens comprised 1,782 articles, 300 book chapters, 216 books, 38 dissertations, 44 conference proceedings (articles), 604 unknown types, and 8 preprints.While many of these documents were authored in English, some were written in other languages such as Spanish, Catalan, Russian, French, Galician, and German.Nonetheless, as the analysis was based on title, keywords, abstract, and references, all documents included this information in English to avoid any bias towards published data in English.publications occurred in the preceding year across all databases.Consequently, there has been a marked growth in the production of forensic linguistics knowledge over the last two decades.which are ranked first and second respectively.The rest of the journals that publish in this field include pragmatics, language studies, law and forensic science.Some of these sources are also available in Spanish.It can be seen in Figure 4d that there are both specific journals to forensic linguistics and other related fields publishing in the field, such as language studies, law and forensic science.

Production of forensic linguistics research by journal and publisher
Figure 5a-b shows the list of top 10 publishers for knowledge in forensic linguistics.As Scopus does not provide publisher information, these lists are limited to the WOS and Lens databases.The first publisher in Scopus is a Spanish publisher, while Elsevier is ranked first in Lens.

Production of forensic linguistics by research area, keywords, and cooccurrence
It is important to note that forensic linguistics is an interdisciplinary field of linguistics that integrates with various other research areas as shown in Figure 6a-c.Based on Figure 6a, the top four subject areas publishing in forensic linguistics are social sciences, arts and humanities, computer science, and psychology.In Figure 6b, the top four research areas associated with forensic linguistics are government law, linguistics, criminology, and criminology penology.In Figure 6c, sociology, linguistics, law, and forensic linguistics are introduced as the top four fields of study.Lens displays more specific fields related to forensic linguistics (e.g., legal law, comparative law, jurisprudence, etc.).

Production of forensic linguistics by authors
It goes without saying that the contribution to forensic linguistics cannot be limited to one or two authors and that an individual article can make a significant contribution to the field.However, our objective was to display the authors who have contributed more knowledge to forensic linguistics (Figure 7a-d).Among the top authors in the field of forensic linguistics, (Cheng & Wu, 2021;Durant, 2022;Mertz, 2007;Parera & Pujolràs, 2021, 2021;Wang et al., 2022) can be seen.

Overview of forensic linguistics studies from Scopus, web of science, and lens
Presented in this section is a scientometric analysis of the retrieved data from Scopus, WOS, and Lens databases based on their scientometric properties.There is a specific focus on highlighting the impact of certain concepts, authors, references, and emerging trends on the field of forensic linguistics through this publication.
CiteSpace was used to determine the top keywords with the largest citation bursts from Scopus and WOS Figure 8a-b.The green line indicates the period during which all research was conducted.Red lines indicate the beginning and end of the burst period.The word with the strongest citation burst in Scopus is speaker identification = 10.31 between 2000 and 2004, and linguistic law = 20.43 between 2016 and 2018 for the WOS.The order of the citations changes when based on their burst duration.While the keyword with longest burst duration in Scopus is priority journal = 1990-2009, it is discourse analysis = 2004-2016 in the WOS data.
Clusters and authors are further illustrated in network visualisations Figure 9a-d.Humanities and linguistics are the most discussed topics in forensic linguistics.According to Figure 9b, language and forensic linguistics are the most discussed topics in published research retrieved from the WOS database.Figures 9c-d illustrate the most cited references and the topics that were searched when citing these references.Some of these topics include statutory interpretation, forensic voice comparison, and others (See Figure 9c).Among the topics included in the WOS database are sociolinguistic evidence, gender violence cases, legal translation, forensic stylistics, and many others (See Figure 9d).
Another important aspect to consider is the co-occurrence of the used keywords.Using VOSviewer, we generated three visual network maps depicting the occurrence of the most frequently used keywords in forensic linguistics across the three databases (see Figure 10a-c).Each colour in the network maps represents a different area of forensic linguistics study.The yellow color indicates studies that specifically focus on keywords related to forensic linguistics.Blue colour represents studies related to legal translation and law, while green colour is associated with speaker identification and forensic science topics (refer to Figure 10a).The may vary depending on the databases used.For example, in Figure 10b, blue colour represents keywords related to language and law, green colour represents words related to sociolinguistics and Catalan evidence, while brown colour indicates forensic linguistic keywords.In Figure 10c, blue colour represents keywords related to forensic voice comparison.
With the help of VOSviewer, we were able to generate three visual network maps for co-citations and citations by authors Figure 11a-c.Each colour represents a co-citation or citation network.The larger the circle, the more co-cited or cited the author is (R. W. Shuy, 2006;Coulthard, 1995;J. Gibbons, 2003), etc., are among these authors.
VOSviewer was used to generate three visual network maps of co-citations and citations by sources Figure 12a-c.Co-citations or source citations are represented by colours.According to Figure 12a, blue journals refer to forensic science, red journals to linguistics, and green journals to conference proceedings.Throughout Figure 12b, yellow represents Spanish journals, green represents speech communication, blue represents pragmatics and interpretation, and red represents forensic science journals.In Figure 12c, blue represents forensic linguistic journals, green indicates language sciences journals, and purple indicates language and society journals.
In order to determine the top 10 cited works, we exported the citation reports from Scopus, WOS, and Lens.As shown in Table 3, the top cited documents were merged and duplicates were removed to produce the final list.The majority of these are in the field of forensic linguistics, while others are in other fields that have used forensic linguistics in some way.

Impact of research on forensic linguistics by clusters, citation counts, citation bursts, centrality, and sigma
Figures 13a-b present a summary of the most commonly used keywords associated with forensic linguistics in both the Scopus and WOS databases, as generated by the CiteSpace software.In comparison to Scopus, where the frequency range is 42-120, the range in WOS is 15-87.In Scopus, the most frequently used word is forensic linguistics, followed by human and linguistics.Forensic linguistics occupies the top position in WOS, followed by linguistic law and language policy.The presented above serve as a valuable indicator of the most frequently discussed topics in forensic linguistics.

Clusters
The network is divided into 22 co-citation clusters in Scopus data Table 4 for the detailed list of clusters.).The largest 8 clusters are summarized as follows.The largest cluster (#0) has 150 members and a silhouette value of 0.818.It is labelled as legal context by both LLR and LSI, and as role (1.39) by MI.The most relevant citer to the cluster is (Coulthard & Johnson, 2010), The Routledge Handbook of Forensic Linguistics.
The network is divided into 15 co-citation clusters in the WOS data.The largest 6 clusters are summarized as follows.The largest cluster (#0) has 109 members and a silhouette value of 0.744.It is labelled as police interview by LLR, forensic linguistics by LSI, and creole continuum courtroom (1.67) by MI.The most relevant citer to the cluster is (Coulthard et al., 2017c), Introduction to Forensic Linguistics: Language in Evidence.

Citation counts
In Scopus, the top ranked item by citation counts is [Anonymous] (1973) in Cluster #3, with citation counts of 295.The second one is (Coulthard et al., 2014) in Cluster #6, with citation counts of 108.In the WOS, the top ranked item by citation counts is [Anonymous] (1999) in Cluster #2, with citation counts of 194.The second one is (Coulthard, 2007b) in Cluster #0, with citation counts of 60.The remaining top authors in forensic linguistics based on citation counts can be found in Table 5.

Bursts
In Scopus, the top ranked item by bursts is (Gibbons, 1994b) in Cluster #0, with bursts of 16.70.The second one is (Rose, 2002) in Cluster #2, with bursts of 14.58.In the WOS, the top ranked item by bursts is (Nogueira López, 2018) in Cluster #7, with bursts of 3.78.The second one is (Cornu,

Centrality
In Scopus, the top ranked item by centrality is [Anonymous] (1973) in Cluster #3, with centrality of 185.The second one is (Coulthard & Johnson, 2010) in Cluster #6, with centrality of 107.In the WOS, the top ranked item by centrality is (Berk-Seligson, 1999a) in Cluster #1, with centrality of 85.The second one is (Coulthard et al., 2014) in Cluster #0, with centrality of 71.For a list of the remaining central authors in forensic linguistics, please refer to Table 7.

Sigma
In Scopus, the top ranked item by sigma is [Anonymous] (1973) in Cluster #3, with sigma of 0.00.The second one is (Coulthard, 2007b) in Cluster #6, with sigma of 0.00.In the WOS, the top ranked item by sigma is (S.Berk-Seligson, 1999a) in Cluster #1, with sigma of 0.00.The second one is (Coulthard et al., 2014) in Cluster #0, with sigma of 0.00.See Table 8 for the remaining authors with potential high citation in forensic linguistics.

Discussion
The purpose of this study was to measure the development of knowledge in the field of forensic linguistics.The latter is now known as "the interdisciplinary field which examines, defines, and investigates language in court as evidence to policies, judges, and lawyers" (Umiyati, 2020, p. 23).
The study results were presented in two distinct sections.The first section provided an overview of bibliometric indicators, including publications by year, the top 10 countries, universities, journals, publishers, subject/research areas, and authors.The second section focused on citations, cocitations, and co-occurrence indicators.Seven significant findings were discussed in relation to bibliometric indicators.Firstly, knowledge production related to forensic has experienced a marked increase over the last two decades.Secondly, the most notable contributors in terms of countries are the UK, the US, and Spain.Thirdly, British universities dominate the list in Scopus and Lens databases, while Spanish universities dominate the list in the WOS database.Fourthly, while there are a few journals that specialize in forensic linguistics, most journals are related to pragmatics, language studies, law, and forensic science.Fifthly, the major publishers in this field Escola Adm Publica Catalunya and Elsevier.Sixthly, several areas related to forensic linguistics were identified, including social sciences, arts and humanities, computer science, government law, linguistics, and criminology penology.The last finding (7) shows that (Cheng & Wu, 2021;Durant, 2022;Matulewska & Gwiazdowicz, 2020;Parera & Pujolràs, 2021, 2021;Wang et al., 2022) are some of the major authors contributing to the field.In accordance with scientometric indicators, we analyzed the most cited keywords in Scopus and WOS.These included language policy (Guimarães et al., 2019), speaker identification (Singh, 2018), speech analysis (Brederoo et al., 2021), law (Carvalho, 2019), andinformation retrieval et al., 2014).They also included linguistic law (Torre et al., 2019), minority language (Limberger et al., 2020), legal translation (Zeifert & Tobor, 2021), forensic linguistics (Umiyati, 2020), and official language (Ward, 2019).
Regarding the most cited authors' latest contributions, number of them, such as (Durant, 2022;Matulewska & Gwiazdowicz, 2020;Parera & Pujolràs, 2021) focused on the juridical part of forensic linguistics rather than on the linguistical one.Others, like (Cheng & Wu, 2021), and (Wang et al., 2022), addressed topics related to the research methods adopted, including critical discourse analysis.
Finally, we performed a Sigma analysis to identify the top-ranked items in both Scopus and WOS.Among the most cited items are court interpreting (S.Berk-Seligson, 1999b), approaches to language in legal settings (Coulthard, 2007a;J. P. Gibbons, 1994a), pragmatics (Coulthard, 2007a), and attitudes (J.Gibbons, 2001a).Our analysis highlighted various topics that are all related to forensic linguistics to a different extent.For instance, court interpreting is an important issue considering that the trial's outcome usually depends on the witness' answers to leading questions.

Practical implications
There are some cautions that should be taken by researchers when interpreting the results of scientometric studies (van Eck & Waltman, 2014) despite the fact that scientometric studies have enjoyed a lot of popularity over the last few years (Moral-Muñoz et al., 2020;van Eck et al., Typically, the process begins with finding data across multiple sources, and avoids using a single database for all analyses, unless there is an adequate justification for doing so (for example in this study, we made use of Scopus, WOS, and Lens for the analysis).To be able to comprehensively analyse scientometric indicators in this study, we should take the next step and make use of different tools in the analysis (e.g., we used both CiteSpace and VOSviewer in this study) to allow us to include a wide range of scientometric indicators in this study.

Theoretical implications
This study has several theoretical implications.Firstly, there is a theoretical implication for higher education policy-makers and educators.The study highlights the significant role of forensic linguistics in academic settings and everyday life situations.As such, it is recommended that forensic linguistics courses be more widely incorporated into higher education curricula.This field should not be limited to students majoring in forensic linguistics, which is relatively scarce globally.
Secondly, the study has implications for researchers, writers, public speakers, YouTubers, and all social media users, TV reporters, news reporters, and media professionals.In contemporary society, there is a rapid proliferation of ignorance concerning copyrights and the rights of others.Therefore, it is crucial to raise awareness among the general public about these rights.

Limitations and future research
This study represents an initial endeavour to investigate the growth and progression of forensic linguistics from a scientometric perspective.Further research is needed to explore the nature of identified clusters related to the field, which could yield additional insights.While this study identified the clusters, it did not examine them in detail, leaving scope for future research to focus on the convergence and divergence of these patterns.Additionally, this study has a limitation in that it did not scope the field of forensic linguistics comprehensively.Although the study provided a brief overview of the history and development of the field, followed by a review of existing literature from 1936 to 2022, a scoping review would entail a more detailed examination of the types of sources and methods employed in forensic linguistics.

Conclusion
The findings of this research provide compelling evidence that research in forensic linguistics has witnessed a significant increase in the last two decades.Our study examined the development and growth of forensic linguistics from 1936 to 2022 using scientometric analysis of 6,460 documents.Through our research, we were able to visualize and analyse forensic linguistics using eight bibliometric indicators and eight scientometric indicators.We have identified the most influential regions and institutions in the field, such as the United States, the United Kingdom, Spain, China, Russia, and others.Additionally, we have identified the most frequently used keywords in forensic linguistics, including human, linguistics, legal translation, language, speech recognition, legal language, authorship attribution, and natural language processing.The keywords also included legal linguistics as a synonym for forensic linguistics, as well as several other areas such as linguistic law, language policy, language and law, official languages, legal translation, and linguistic rights.Moreover, the significant benefit of our scientometric analysis was the ability to categorize the 6,460 documents in forensic linguistics into several clusters based on research patterns.Some of these patterns include the role of forensic linguists in legal contexts, legal translation, legal composition, forensic voice comparison, authorship attribution, and human language technologies.Other clusters included the use of forensic linguistics in police interview settings, public service settings, and courtroom settings, linguistic rights, and online debates.

Funding
No funding was received for this paper.
• The scope of forensic linguistics has expanded to include speech detection, text detection, plagiarism detection, social media verbal violence detection, social security detection, and discrimination detection.
• A scientometric analysis of 6,490 triangulated documents from major knowledge databases was conducted to examine the development of forensic linguistics.
• The study identified commonly used keywords in forensic linguistics and grouped the 6,460 documents into various clusters based on research patterns in the field.These clusters included the role of forensic linguists in legal contexts, legal translation, forensic voice comparison, authorship attribution, and human language technologies.

•
Stylistics and questioned authorship • Semiotics • Stylometry and statistical methods • Document examination and plagiarism detection • Linguistic dialectology • Corpus linguistics and forensic software • Language of courtroom • Language and law • Interpretation and translation.

Table 1 .
Bibliometric and scientometric indicators for measuring forensic linguistics development, adapted from (Alduais et al.the frequency of a certain event in certain period (e.g., the frequent citation of a certain reference during a period of time) (Kleinberg, 2002) √ Χ Co-citation When two references are cited by a third reference (C.

Figure
Figure 1.Forensic Linguistics Knowledge Production Size by Year.

Figure
Figure 2a-c presents the top 10 countries that have produced knowledge related to forensic linguistics.The UK and the USA are ranked first and second, respectively, in Scopus and Lens

Figure
Figure 4. Forensic linguistics knowledge production size by source.

Figure
Figure 3a-c presents the top 10 universities and/or research centres producing knowledge in forensic linguistics.Despite the fact that most of the universities in the Scopus database are British universities, they are Spanish universities in the WOS database.Lens presents a variable list of institutions, but the majority of them are British universities including the Aston Institute for Forensic Linguistics.

Figure
Figure4a-c demonstrates the top 10 journals publishing research in forensic linguistics.As can be seen from the Scopus index, there are a number of journals that specialize in forensic linguistics, Figure 7. Forensic Linguistics Knowledge Production Size by Author.

Figure 8 .
Figure 8. Top 10 Keywords with the Strongest Citation Bursts.

Figure
Figure 9. Top Keywords, Cited Authors, and Clusters.

Figure
Figure 10.Cooccurrence by author keywords network visualization.
Figure Most Frequent Keywords in ForensicLinguistics.

Figure
Figure 14.Top 10 cited authors and references with the strongest citation bursts.