The Politics of Taxes for Health: An Analysis of the Passage of the Sugar-Sweetened Beverage Tax in Mexico

ABSTRACT This article explores the politics of passage of the sugar-sweetened beverage (SSB) tax in Mexico, using published documents, media articles, and interviews with key stakeholders. The article examines first the period of agenda setting when the tax was included in the President’s fiscal reform package; and second, the period of legislative passage, when the bill was introduced in Congress and was passed. The analysis uses Kingdon’s three streams theory of agenda setting, to explain how the tax emerged on the agenda and how agenda setting shaped and enabled legislative passage. The article offers five lessons related to the politics of passing the SSB tax in Mexico. First, passing an SSB tax was difficult and required high-level organization, cooperation, planning, and effort. Second, supporters needed an understanding of how to manage the political and economic context, facilitated by a grant from Bloomberg Philanthropies. Third, framing the tax as generating revenue helped get the proposal onto the policy agenda and enabled buy-in from the powerful Ministry of Finance (Hacienda). Fourth, forming networks within the legislature early on allowed tax proponents to have a network of allies within Congress ready when the SSB tax was introduced as a bill. Finally, early public relations campaigns helped shape public perception that Mexico’s obesity epidemic was driven in part by SSB consumption. This is the first paper that uses political science theory and primary data collection and interviews with a broad range of stakeholders, to explain how Mexico passed an SSB tax despite opposition from a strong national SSB industry.


Introduction
Mexico and many countries around the world are grappling with the rise of non-communicable diseases (NCDs). 1,2As countries become increasingly urban and economies grow, their population undergoes a nutritional transition in which under-nutrition is rapidly replaced by a rise in obesity and associated NCDs. 1 Mexico has experienced one of the fastest rises in type 2 diabetes mellitus, driven by the equally dramatic increase in overweight and obesity. 2,3Public health experts in Mexico and around the world have identified the sharp increase in consumption of sugarsweetened beverages (SSBs) as one of the major causes of the global obesity epidemic. 4,5n October 2013, Mexico passed a tax on SSBs.The tax, which took effect on January 1, 2014, is an excise tax of one peso per liter (about 10% of SSB retail price) on any beverage sweetened with sugar, excluding alcoholic and dairy products. 6The tax provided significant additional revenue for the Mexican government, and also reduced SSB consumption by between about 6% and 10%, thereby helping to address the obesity epidemic in Mexico. 7,8exico was the first country in the Americas to pass an SSB tax, and its passage in 2013 marked increased global interest in SSB taxes. 9Prior to 2013, only 9 other nations had passed SSB taxes, but since Mexico passed its SSB tax, around 23 other nations and eight jurisdictions in the US have adopted a tax on SSB. 9,10Not all attempts to pass SSB taxes have been successful.In 2016, the proposed SSB tax in Colombia did not pass in the face of organized opposition from the soda industry. 11Although many countries have successfully adopted taxes on SSBs, little is known about the politics of adopting these measures, particularly in the context of SSB industry opposition.
This research fills a gap in the knowledge and publications about the passage of Mexico's SSB tax and about the passage of "sin taxes" more generally.Two other studies examined the politics of passing the SSB tax in Mexico.One is a report by the Pan American Health Organization (PAHO) that analyzes the passage of the tax in Mexico and also the initial effects of the tax on health outcomes. 12The report focuses on the role that PAHO played in promoting the tax and concludes that the tax was passed as a result of a confluence of political, economic, epidemiological, social, inter-sectoral and global factors. 12he second study examines the strategies that civil society advocates used in working for the tax passage. 13The study focuses on the use of paid and earned media as the primary means of influencing legislators. Neither study analyzed how the strategies used by tax proponents and opponents affected agenda setting or the legislative passage of the SSB tax in the Mexican Congress. 12,13his paper uses qualitative methods and direct field research, combined with social science theory, to explain the legislative passage of the Mexican SSB tax in spite of a powerful SSB industry.We use John Kingdon's three streams theory on agenda setting to explain how the tax emerged on the agenda and how the process of agenda setting shaped and enabled the legislative passage of the tax. 14ollowing this introduction, the paper presents background on the tax, the key players, political context, and the breakdown of the votes in the Mexican Congress.We then explain Kingdon's three streams theory, including why it was chosen and how it was used to guide the analysis.Next follows the data and methods section, where we explain why we did stakeholder interviews, how we identified stakeholders, and how we analyzed the data.We then present the results of data analysis and explain why the pro-tax side was able to cooperate more effectively, and how the period of agenda setting influenced legislative passage.Finally, we present our conclusions and the limitations of the study, and suggest the lessons learned.

Background
The SSB tax had potentially huge implications for large multinational corporations in Mexico, like Coca-Cola and PepsiCo, that sell sugar-sweetened beverages. 15The ties between the SSB industry and Mexican society are pervasive, with Coca-Cola integrated into many areas of Mexican society.Coca-Cola has regularly sponsored sporting events throughout the country for over 17 years; and in 2000 Vicente Fox, who was previously chief executive of Coca-Cola Mexico, was elected as President of Mexico. 15Coca-Cola also has developed extensive ties to the health sector in Mexico.The company has co-sponsored events with the Mexican Diabetes Association, supported a government exercise initiative aimed at combating childhood obesity, and co-sponsored a public health prize with the National Council of Science and Technology for best scientific research on diet, health and well-being. 15,16hile the ties between Coca-Cola and Mexican government and society are well known, they were not the only groups potentially affected by the SSB tax.The tax also had implications for the supply chain for SSBs, including Mexican sugar producers, SSB bottlers, and stores selling SSBs.These groups were represented by their own organizations, such as the Alianza Nacional de Pequeños Comerciantes (ANPEC), which represents small businesses, and trade groups, such as the Unión Nacional de Cañeros, which represents the sugar cane industry.The SSB companies did not involve themselves directly in combating the tax, rather they used their representatives, such as the Asociación Nacional de Productores de Refrescos y Aguas Carbonatadas (ANPRAC; National Association of Soda and Carbonated Beverage Producers) and through the lobbyist organization, Consejo Nacional de la Industria de Productos de Consumo (CONMexico).These groups, which we henceforth refer to as opponents to the tax, launched an offensive against the proposed tax on SSBs.These groups advertised widely against the tax and urged politicians in the Mexican Congress to oppose the tax, arguing that the tax would harm small businesses and employment, was regressive in its economic effects on poorer citizens, and would not affect obesity rates. 17he proposal for an SSB tax received strong support from civil society, academics, and politicians.In the sphere of civil society, El Poder del Consumidor (Power of the Consumer), a non-governmental organization (NGO) focused on consumer rights, helped found an umbrella organization of 22 NGOs and 650 civil society groups known as the Alianza por la Salud Alimentaria (Alliance for Food Health).This group supported the tax from a consumer rights perspective.One of their key allies in the civil society sphere was another alliance, called Contrapeso (Counterweight), a coalition of 40 civil society organizations, focusing on supporting the tax from a public health perspective.In terms of academics, the largest and most vocal supporters came from the Instituto Nacional de Salud Pública (INSP; National Institute of Public Health), whose researchers estimated the effects of an SSB tax on beverage consumption and on health.While these groups worked for many years prior to 2012 to promote an SSB tax, it was not until mid-2012 that the supporters of the tax were able to organize effectively.A 10 million USD grant from Bloomberg Philanthropies in 2012 provided a major boost to the proponents of the SSB tax, allowing them to hire a political strategy and lobbying firm and to design and implement advocacy efforts inside the national government and to the Mexican public. 13he elections of 2012 brought a new government to power in Mexico, and this presented an opportunity for the tax proponents to pursue SSB tax legislation.In 2012, the PRI (Partido Revolucionario Institucional) won the presidency, however, they lacked a majority in the Senate and the House of Deputies.The three major political parties, the PRI, the PAN (Partido Acción Nacional), and the PRD (Partido de la Revolución Democratica), then announced an agreement to work together in the Pacto por Mexico (PPM).The three parties agreed to a set of 95 initiatives in five categories: 1) rights and liberties; 2) democratic governance; 3) security and justice; 4) transparency and combating corruption; and 5) economic growth, employment and competitiveness. 18mong the issues that the PPM proposed to address was Mexico's slowdown in economic growth, in part due to a reduction in oil prices and slowing oil production. 19The PPM expressed a need to increase government revenues to fund social programs and government functions, which the Pact planned to accomplish through a large fiscal reform.Within the new government, the SSB tax proponents successfully organized support in the Mexican legislature, which resulted in the tax being initially presented by PAN Senator Marcela Torres Peimbert, on December 11, 2012. 20While this Senate bill was eventually set aside in preparation for the upcoming presidential fiscal reforms, the Ministry of Finance (Secretaría de Hacienda y Crédito Público and referred to hereafter as Hacienda) decided to include the SSB tax as part of its fiscal reform bill.In what followed, the SSB tax was pushed by Hacienda, without much input or support from the Ministry of Health (MoH).
The tax proposal garnered high-level political support from President Enrique Peña Nieto, who introduced the bill in Congress as part of his fiscal reforms in 2013. 21The SSB tax was introduced as part of the Impuesto Especial sobre Productos y Servicios (IEPS), a package of direct taxes, traditionally levied on tobacco products, alcohol, beer and gasoline.The tax was ultimately passed by an alliance between three political parties, the PRI, the PRD, and the PVEM (Partido Verde Ecologista de Mexico).On October 17, 2013, the House of Deputies voted to pass the bill passed with 317 votes in favor (207 PRI, 73 PRD, and 25 PVEM votes) and 164 votes against (113 PAN and 23 PRD votes). 22Meanwhile, on October 29, 2013, the Senate voted to pass the bill with 73 votes in favor (54 PRI, 1 PAN, 10 PRD, and 7 PVEM votes) and 50 votes against (36 PAN and 9 PRD votes). 7e identified two stages in the passage of the SSB tax: first, getting the tax adopted as part of the government's fiscal reform, and second, getting the tax passed in the Mexican Congress (Figure 1).The first stage takes place between mid-2012, when the tax proponents began cooperating after they received a grant from Bloomberg Philanthropies, until the tax was announced as part of the President's fiscal reform package on September 8, 2013.The tax was then sent to the Mexican Congress for consideration, which initiated the second period, focused on the passage of the tax at the end of October, 2013.While the first period is notable for the lack of participation of the SSB industry, the second period features open conflict between the tax proponents and opponents.Given that these two stages involve different processes, players, and strategies, we analyze them in turn.In the first period, we use Kingdon's three streams theory to analyze how the tax proponents set the agenda and got the tax included as part of the presidential fiscal reforms.Then we turn to the period of legislative passage and examine key factors that enabled it to successfully pass in the Mexican Congress.

Conceptual framework
This research uses a conceptual framework originally developed by John Kingdon to explain how agendas are set within the US federal government. 14Agenda setting is an important stage in the development of government policies as it restricts the set of problems being addressed and the set of policy alternatives under consideration.Kingdon's theory has been used frequently to explain health policy processes in many situations, 23- 25 including an analysis of how some US state legislatures passed SSB taxes. 26We use the theory to explain agenda setting for the SSB tax in Mexico: how the SSB tax went from a policy idea without much support to its adoption as part of Mexico's 2013 fiscal reform.
Kingdon identifies three different streams that when present at the same time make a policy more likely to rise on the government's policy agenda.The first is the problem stream that explains how conditions become problems, which occurs when government officials become aware of conditions and then decide to address them.Conditions come to the attention of policy makers through indicators, such as illness rates, focusing events, such as an economic crisis, and feedback, such as routine monitoring or complaints.Once a condition is identified, it does not necessarily become a problem.Conditions are more likely to become a problem if they go against a prevalent norm, or are poor in comparison to other nations.The definition of the condition also is important in whether it becomes a problem; for example, if obesity were defined as an individual failure of self-control then it might be less likely to be framed as a problem by policy makers.
The second stream is the politics stream, which is independent of the other streams, and refers to how events such as new administrations, changes in national mood, and organized interest groups have the ability to help set the agenda.In this stream, consensus is reached by bargaining, where politicians trade favors for support.In this stream, visible participants, such as the President, high-level cabinet members, senators and deputies, are more likely to affect the agenda.
The third stream is the policy stream through which alternatives are generated and selected.Kingdon calls this the "policy primeval soup" where ideas "float around, bumping into one another, encountering new ideas, and forming combinations and recombinations." 14The origin of policies may be hard to trace; however, the ways in which they evolve follows a logic according to their political acceptability for the public and politicians as well as their technical viability, meaning whether they are implementable and whether the process of implementation is understood.The alternatives are generated by policy specialists, who, in contrast to people in the politics stream, may be relatively hidden.These specialists include academics, bureaucrats, researchers, and consultants.The more united these specialists are, the greater the likelihood that they agree on a small set of alternatives and the more likely the policy alternatives are to survive and thrive.These policy specialists or entrepreneurs push their ideas in different forums, in a process known as "softening up," so that both the public and politicians become familiar with the policy before it is introduced as legislation.Sometimes this is done through hearings and public discussions, or by floating trial legislation with the understanding that it will not pass this time but might at a future date.
When problems arise under favorable political circumstances and become coupled to an existing solution, there is a window of opportunity when policies are more likely to come on to the government's decision agenda.During these windows of opportunity policy entrepreneurs push their policy solutions.Windows are opened by the problem or the politics stream and are sometimes predictable, as happens for budgetary legislation that appears at regular intervals, or unpredictable, as happens for accidents.While Kingdon explains that the coupling of the three streams creates a window of opportunity, detailed case studies help us understand how the three streams are brought together and the broader implications.Our analysis explores how these streams came together in Mexico for the SSB tax, particularly how policy entrepreneurs assessed the three streams and helped bring them together to produce a window of opportunity and legislative change.

Data and methods
This research relies on three sources of data: documents from government, international organizations, and civil society groups; media articles; and key informant interviews.The majority of our analysis relies on key stakeholder interviews, guided by Kingdon's theory of agenda setting.

Identifying key stakeholders
We used two sources to identify key stakeholders: government documents and newspaper articles.We searched legislative documents from the Mexican Senate and the Chamber of Deputies, including minutes of proceedings, proposals, presentations, and reports, between September 2012, when the newly elected legislators took office, through December 2013, after the SSB tax had been passed and signed by the President.We searched these documents for any mention of a tax on sodas or SSBs, obesity, overweight, or diabetes in order to construct a database with the dates, names of the legislators who introduced the topic, their party, and a brief summary of what was said.Using the same keyword search and date parameters, we generated a second database of press articles through "Nexis Uni" focusing on Mexican newspapers.These two databases allowed us to identify visible participants in the passage of the SSB tax, including legislators, bureaucrats, politicians, academics, civil society, and NGOs, whom we asked for interviews.We also used the snowballing method to identify additional stakeholders by asking participants who was important in the passage of the tax.Snowballing is a purposeful sampling method used in qualitative research to identify participants who are behind the scenes or hidden, but may be important in a public policy decision. 27

Stakeholder semi-structured interviews
After we identified key players in the passage of the tax, we sent them an email inviting them to participate, which included a description of the project, the procedures, the types of questions involved, and a copy of the consent form.We obtained approval from both the Instituto Nacional de Salud Pública's Ethics Committee (protocol number 1490) and from the Harvard T.H. Chan School of Public Health (protocol number IRB17-1928) to conduct the study.Participants were interviewed privately in person, on skype, or by phone.Interviewees were required to sign an informed consent where they agreed to have the interview taped and that explained the study risks.The recordings of the interviews were deleted after transcription, and we refer to participants by interview number and their relationship to the passage of the tax, such as senator, NGO employee, or lobbyist.
The interview guides had lines of inquiry divided into two periods, the agenda-setting period and the legislative passage period.In order to avoid imposing our own conceptions on the passage of the tax, we left the questions open ended and allowed interviewees to emphasize aspects that they thought were important.We continued interviewing until we stopped uncovering new themes.We conducted a total of 17 interviews, across eight different groups of stakeholders, as shown in Table 1.

Analytic method
Interviews were conducted and transcribed in Spanish.Analysis of the interviews began by identifying the key players mentioned, their strategies, and the context during the two periods.We then reviewed the interviews again, this time guided by Kingdon's three streams model to identify how the agenda was set.Within the agenda-setting period, we looked for themes from the model that were reflected in the interviews.The third step in our analysis involved triangulation to look for agreement between what was said in interviews, and what appeared in published articles and other documents.We used this analysis to construct an explanation for how the SSB tax rose to prominence on the agenda and how it was ultimately passed by the Mexican legislature.

Politics stream
The politics stream began opening with Mexico's 2012 elections that brought a new government to power.The new President had promised fiscal reforms as part of his platform.Political strategists advocating for the SSB tax explained that they conducted political mapping and analyzed the political context, so they were aware that there was an opening of the political stream. 28These strategists knew about plans for a fiscal reform in the fall of 2013 and they positioned and framed the SSB tax so that it would fit in the reform.Tax proponents also recognized that the first year of a new administration is the optimal time for legislative change, since the new government has a new set of subjects on its decision agenda, making it a good time to get new policies passed. 29Timing is key, since after the first year of an administration, as one academic explained, cooperation between political parties generally decreases and in the case of the SSB tax it would have likely allowed opponents to the tax more time to lobby government officials. 29he PPM was also important in indicating to the tax proponents that the political environment might be favorable for an SSB tax. 280][31][32][33][34] The political strategists assisting the tax proponents assessed the political context and predicted the opening of the politics stream, so they began working to link this stream with the problem stream and the tax policy to ensure that the SSB tax was included in the President's fiscal reform package and became part of the government's decision agenda. 28his strategic assessment of the political context in the new administration also helped the tax proponents decide to engage solely with Hacienda to push the tax, rather than also trying to involve the MoH. 30,32cademics and NGOs were aware that the new Secretary of Health, Mercedes López Juan, had worked closely with the food and beverage industry at her previous job and had made public statements against the tax and in favor of health education as a means to combat obesity in Mexico. 29,32,35They were also aware that not only was Hacienda the more powerful government institution but that they also had the ability to set taxes, which the Ministry of Health lacked. 32The political strategists, academics from INSP, and NGOs, including El Poder del Consumidor and Contrapeso, all stated that they decided to go through Hacienda, without seeking support from the MoH, since they believed they would encounter opposition to the tax from the Secretary of Health. 30,32,34oblem stream At the same time in 2013, Mexico's new administration faced an economic crisis as the price of oil began to drop. 19A government report outlining Mexico's economic outlook reported an unexpected slowing in economic growth producing an estimated budget shortfall of 74 billion pesos (0.5% of gross domestic product) compared to the approved budget for 2013, largely due to the falling production and price of oil. 19,36Many advocates for the tax, including academics who spoke with Hacienda in early 2013, were well aware of the need for additional sources of government revenue and worked to place the SSB tax in this light. 33,34One interviewee stated that the need for additional revenue was the main factor driving Hacienda to include it as part of the 2013 fiscal reform. 33The need for additional government revenue helps explain why the idea of new taxes was well received, but it does not explain why a tax on SSBs was included in the fiscal reform.
The focus on a SSB tax occurred partly through the publications by academics on Mexico's obesity epidemic, which became part of the problem stream.][39][40][41][42][43] Subsequently, studies linking the obesity and diabetes epidemics to the increasing consumption of SSBs were published. 4,33,34,43In the spring of 2013, some academics held meetings with officials from Hacienda, providing the officials with research showing a huge increase in obesity and diabetes rates and identifying a major driver as the increase in consumption of SSBs. 43,44One interviewee explained that Hacienda used this evidence in their arguments on the need for the tax when it was included as part of the fiscal reform. 45eanwhile, NGOs used these research studies to increase public and government awareness of the problem of SSB consumption and associated health problems.El Poder del Consumidor and the Alianza por la Salud Alimentaria brought visibility to the obesity epidemic through public demonstrations, such as one held in October 2012 where demonstrators dedicated an altar on the Día de los Muertos (Day of the Dead) to those who died from diabetes between 2006-2012. 46hey also organized paid advertising campaigns, such as the "First obesity, then diabetes" campaign that used graphic images on billboards of individuals with amputations from diabetes. 13,30These NGOs linked the consumption of SSBs to the obesity epidemic using public demonstrations and advertising campaigns, which included the provocative question of "Would you give them 12 spoons of sugar?" associated with a bottle of soda. 13,30,47Once the NGOs established the relationship between obesity and SSBs in the public's mind, they moved on to advocate for the adoption of an SSB tax as the means to address the problem. 13,30These media campaigns were very successful in conveying the magnitude of the obesity and diabetes epidemics in Mexico; indeed, one bureaucrat explained that a public perception emerged that the epidemics were so severe that the government had to do whatever it takes to address the problem. 45nternational pressure also pushed Mexico to address the obesity epidemic, and contributed to the emergence of obesity and diabetes as problems on the government's decision agenda.In 2011, the United Nations Special Rapporteur on the Right to Food called on Mexico to declare a state of emergency in response to the obesity epidemic. 48The Organization for Economic Cooperation and Development (OECD) highlighted the scale of the obesity epidemic in Mexico and urged action. 49One government official interviewed stated that material provided by the Pan American Health Organization (PAHO) was used to frame and explain the problem of obesity and diabetes when Hacienda sought to justify the tax as part of the fiscal reform. 44

Policy stream
The idea for an SSB tax as a means of addressing the obesity epidemic was not new in Mexico. 44,45As part of the multisectoral government program called the Acuerdo Nacional de Salud Alimentaria, under the previous administration of President Calderon, there were discussions between the MoH and Hacienda to use an SSB tax as a means of alleviating the obesity epidemic; however, these discussions came late in the administration's term and the tax was never passed. 29iming was an important factor in 2013, since previous efforts lacked the government's budget shortfall that the tax also proposed to solve and the earlier efforts came late in the Calderon administration when a political window for policy change was not open. 32he major difference in 2012 and 2013 was the strategic cooperation between the NGOs, academics, and political lobbyists, made possible through the funding provided by Bloomberg Philanthropies.When Bloomberg Philanthropies began looking into the possibility of working to address the obesity epidemic in Mexico, they gathered a group of NGOs, academics, and a lobbyist to discuss what could be done. 30loomberg Philanthropies decided to support these organizations by providing money, which allowed these groups to develop and expand their activities to promote the tax. 30One participant explained that the influx of money allowed them to hire a professional political strategy firm and to launch major paid media campaigns, whereas previously they had relied on their own political analysis and on "earned" media campaigns, meaning press coverage of events. 30erhaps equally important was the impetus the Bloomberg Philanthropies grant provided for these different groups to work together strategically.The external funding helped create agreement among NGOs, academics, and the lobbyists that they all collaborate together on pushing the SSB tax, rather than work separately to promote the tax.Several participants explained that the public health NGOs, under Contrapeso, directly lobbied Hacienda and the legislature, while the consumer rights NGOs, led by Poder del Consumidor, focused on public awareness campaigns in the media. 28,30,32,50Indeed, this cooperation was strategically designed, with the political strategists proposing the division of labor according to each group's strengths in the political and public spheres, while also finding a champion within the legislature to begin the work of softening up the government for policy change. 28hrough their own political mapping, the political strategists explained that they recognized the need for a champion within the legislature to introduce the idea of an SSB tax and they identified several potential legislators. 28,32Their main proposal within the Senate was Marcela Torres Peimbert of the PAN, who proposed an SSB tax in December 2012. 28By selecting someone from the conservative opposition party that traditionally favors business, the tax proponents gained political legitimacy for the tax proposal. 28This proposal allowed the Senator the opportunity to familiarize the legislature with the tax and gather support as 37 deputies and 13 other senators eventually signed on to support the bill. 20,28This also softened up Hacienda, by signaling that legislators were amenable to the tax, while also introducing the policy as a solution to the obesity and diabetes epidemics as well as the expected national revenue shortfall.
Meanwhile, academics and experts in the public health community, such as PAHO, continued meeting with Hacienda to provide them with studies on the technical feasibility of the tax and its likely impacts on consumption. 44Public health researchers produced estimates on the price elasticity of demand for SSBs as well as the cross-price elasticity of demand for alternatives. 4,33Studies found demand for SSBs was elastic, meaning a rise in the price of SSBs would lead to a decline in consumption, however, demand was not so elastic that consumers would stop drinking SSBs altogether. 33,34,43These studies also found that substitutes for SSBs were healthy, so consumers would probably switch to healthier products in response to a rise in price of SSBs. 33,34,43[45]

Legislative passage
Once the President announced that the SSB tax would be part of the fiscal reform, Mexico's SSB industry began lobbying against the proposal.][53] Partly because of Hacienda's strategy of secrecy, the SSB lobby failed to anticipate the tax.One trade group reported that it repeatedly warned people in the SSB industry that the tax was coming in Spring 2013, however those warnings went unheeded, perhaps because the industry was unaccustomed to conflict with the government and the industry may have wanted to avoid conflict until they were certain the tax was coming. 54This failure to anticipate the tax meant that the industry lost important time in opposing the policy. 54This led to an inability of industry lobbyists and trade groups to frame the obesity epidemic as a result of an imbalance of calories and lack of exercise, since the tax supporters had already framed the issue as driven by excessive SSB consumption.
While the SSB industry was waiting for the formal announcement of the legislative proposal, the tax supporters had already been working to push for the tax.Concerted cooperation during agenda setting meant that the tax supporters were strategically better prepared to lobby Congress and that they had already secured key allies within the Congress.Indeed, when those opposed to the tax went to lobby Congress, the political strategists supporting the tax were told of these activities by their allies in Congress. 28,32he third element that contributed to the passage of the SSB tax was the nature of politics in Mexico.Until recently, Mexican politicians were unable to serve consecutive terms in the Senate or the House of Deputies, meaning that once their term was up they had to find other positions, often assisted by their political party. 55he reelection prohibition combined with the role that the parties played in moving politicians from one elected position to the next created significant party loyalty. 56Since the SSB tax was a presidential reform, it meant that all members of the President's PRI party were almost certain to vote in favor of the policy.

Discussion
This paper explains the successful passage of the SSB tax in Mexico, as a single case study, using published documents, media articles, interviews with key stakeholders, and Kingdon's theory of agenda setting.We found that one of the major factors that contributed to success was the financial support provided by Bloomberg Philanthropies, which allowed for the hiring of professional political strategists who understood and analyzed the political economy context, and the purchase of significant public media communications.Knowing that the politics stream was opening with the Pacto Por Mexico signed, the start of a new administration, and a promised fiscal reform, the tax supporters created an alliance of NGOs and academics and legislators to bring the problem and policy streams together and put the SSB tax on the legislative agenda as part of the fiscal reform.Together with academics, Contrapeso, El Poder del Consumidor and many other NGOs, the political strategists brought public awareness and government attention to the problem that SSB consumption was contributing to Mexico's high rates of obesity and diabetes; these actions aligned the politics and problem streams.The SSB tax already existed as a policy solution to the obesity and diabetes epidemics, but the tax supporters used alliances with Senators and members of the House of Deputies to raise the profile of the tax to Hacienda and within the Mexican Congress.The merging of the three streams brought the SSB tax into the President's fiscal reform.
We found that the politics of agenda setting were different from the politics of legislative passage, insofar as participants and strategies were different.Our analysis also showed that careful agenda setting can pave the way for successful legislative passage.Hacienda designed its own strategies for passage, separate from those of civil society supporters, by using secrecy while preparing the tax as part of the fiscal reform.This strategy helped prevent the tax opponents from becoming an effective force against the tax.Hacienda's secrecy on the proposal and the growing ties between the legislature and the tax supporters created conditions that enabled the legislative passage of the tax.The tax opponents had less time to respond to the tax, and their strategy to engage in a public debate against the tax failed to have much impact, as the relationship between obesity and SSBs was already widely known and accepted by the public.
This study offers important insight into the passage of the SSB tax in Mexico, but the study does have some limitations.One important limitation is that it is a single case study, so the findings may not be generalizable to other places.There may be other possible explanations for how the tax was passed.25]57 There also is the possibility of bias in the selection of interviewees, if those who were against the tax were less likely to agree to be interviewed.In addition, there is the danger of bias, since passage of the tax may affect how participants view past events.We attempted to attenuate this potential bias by triangulating information and using media articles and other documents in addition to interviews.Despite these limitations, there are certain findings that may be applicable to other countries and cities seeking to pass an SSB tax.The first is that the three streams model could be a useful tool in developing strategies to pass SSB taxes, as it provides a framework for thinking about the conditions necessary to achieve policy passage.Second, passing an SSB tax is difficult and involves high-level organization, cooperation, strategic planning, and effort.In order to develop political strategies to pass the tax, an understanding of the political and economic context is crucial.Academics and NGOs played critical roles in Mexico in generating scientific analysis and presenting the results to both the public and government officials.Revenue generation is a powerful tool in getting such taxes onto the agenda and enables buy-in from the Ministry of Finance, which in this case was crucial, since within the government, Mexico's policy was an Hacienda-driven reform with little involvement from the Ministry of Health.Forming networks within the legislature and the Ministry of Finance early on is important, as are early public relations campaigns to shape public perception that the obesity epidemic is driven in part by SSB consumption.It is also important to emphasize the role that funding, in this case from Bloomberg Philanthropies, can have in enabling the development and implementation of unified and effective political strategies among tax proponents.Finally, while the public health community has learned from the experiences of passing or failing to pass such tax reforms, the SSB industry and their allies are also learning and changing their strategies.

Figure 1 .
Figure 1.Timeline of the passage of the SSB tax

Table 1 .
Number of interviews conducted with key stakeholders in Mexico