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How Should Elected Politicians Behave? Constitutional Insights from the U.S. and Brazilian Supreme Courts

By Arthur Guerra Filho

What do we expect from elected politicians? Should they champion the interests of those who elected them—or act as trustees for the broader public good? Or perhaps a complex combination of them? This is not only a philosophical question but a constitutional one: in practice, many boundaries of acceptable political behavior are shaped by courts. When apex courts rule on political finance (that is, the financing of political parties and electoral campaigns), they define the boundaries between private and public interests—and, in doing so, they help to shape the contours of democracy itself.

This post examines how two influential apex courts—the United States Supreme Court and the Brazilian Supreme Court—have approached this question through their decisions on political finance. Corruption scandals in political finance have shaken both the U.S. and Brazil, the two largest constitutional democracies in the Americas, forcing their Supreme Courts to deal with political finance issues. They share structural parallels—presidentialism, federalism, and multiethnic societies rooted in profound inequality—yet have charted different courses in regulating political finance.

The U.S. and Brazil’s supreme courts’ rulings reveal contrasting visions of democracy, each with its strengths and weaknesses, and they illuminate how judicial interpretations can reinforce or reshape democratic norms.

Why Courts Matter in Defining Democracy

Courts may often interpret foundational principles—like free speech, equality, and corruption—in ways that directly affect how democratic politics works. Political finance cases bring this role into focus. By deciding what kinds of financial influence are permissible, apex courts set constitutional limits on political activity: which donations are legitimate, which lobbying practices are tolerated (or even welcomed), and when private benefits cross the line into criminal bribery. In effect, these decisions articulate judicial answers to the question: how should elected politicians behave?

Picture of the US Supreme Court.
The Supreme Court of the United States, Washington. Photo by Jesse Collins via Wikimedia Commons.

Two Conceptions of Democracy

While there are many nuances, this discussion focuses on two main models of courts’ approach to campaign finance: the interest pluralist and the republican.[1] Each reflects a broader vision of how private interests should relate to the public good. Real courts may not fully embody either, but they often lean toward one or the other.

The U.S.: Interest Pluralism

The majority of the U.S. Supreme Court has developed what scholars call an interest pluralist approach. Under the interest pluralist model, democracy is seen as a competition among private interests, with legitimacy arising from the electorate’s ability to evaluate and choose among them.[2] Drawing on James Madison’s Federalist No. 10, the Court assumes that private interests are inevitable in politics—and that their competition can even be beneficial. Rather than seeking to eliminate private influence, the Court aims to manage it, trusting that a robust “marketplace of ideas” will allow voters to evaluate competing claims.

This logic is evident in landmark cases like Buckley v. Valeo (1976) and, particularly, in Citizens United v. FEC (2010). In Citizens United, Justice Anthony Kennedy, writing for the majority, famously declared that “ingratiation and access are not corruption.” The majority held that corporations and unions have a constitutional right to spend unlimited amounts on independent political advertisements, framing such expenditures as protected speech under the First Amendment. For the Court, influence and responsiveness are not only tolerable but central to representative democracy—provided that politicians retain their “best judgment” and avoid quid pro quo arrangements. Writing for the majority, Justice Kennedy argued that:

The fact that speakers may have influence over or access to elected officials does not mean that these officials are corrupt:

“Favoritism and influence are not… avoidable in representative politics. It is in the nature of an elected representative to favor certain policies, and, by necessary corollary, to favor the voters and contributors who support those policies. It is well understood that a substantial and legitimate reason, if not the only reason, to cast a vote for, or to make a contribution to, one candidate over another is that the candidate will respond by producing those political outcomes the supporter favors. Democracy is premised on responsiveness.” McConnell, 540 U. S., at 297 (opinion of Kennedy, J.).

[…] The appearance of influence or access, furthermore, will not cause the electorate to lose faith in our democracy.[3]

Justice Kennedy grounded his opinion in the Madisonian view that factions—understood as the pursuit of private interests by interest groups and political parties—are an inevitable feature of U.S. representative democracy because:

[T]he remedy of “destroying the liberty” of some factions is “worse than the disease.” The Federalist No. 10, p. 130 (B. Wright ed. 1961) (J. Madison). Factions should be checked by permitting them all to speak, see ibid., and by entrusting the people to judge what is true and what is false.[4]

This reasoning extends to criminal law. In McDonnell v. United States (2016), a unanimous Court overturned the bribery conviction of a former Virginia governor who had accepted luxury gifts and loans in exchange for arranging meetings and events. The Court held that such actions did not qualify as “official acts” under federal bribery statutes, warning that an overly broad definition could criminalize routine political interactions and chill democratic engagement. As Chief Justice Roberts put it, “Officials might wonder whether they could respond to even the most commonplace requests for assistance, and citizens with legitimate concerns might shrink from participating in democratic discourse.”[5]

Brazil: Republicanism

Brazil’s Supreme Court has charted a strikingly different course, rooted in a republican ideal. The republican model views representative democracy from a broader perspective, in which elections are just one of its elements. Representative democracy is seen as a holistic political process that emphasizes public deliberation and cooperation (rather than elections alone) as the foundation of healthy democracy.[6] Central to this vision is the notion that public office must be exercised exclusively (or at least predominantly) for the common good—a contrast to the U.S. Court’s acceptance of private interests as inevitable. The Brazilian republican approach is intertwined with the concept of patrimonialism, which has long served as an analytical lens to criticize Brazilian political culture for its alleged blurred line between public and private spheres. In this view, the state has historically been treated as a source of private enrichment, and combating corruption requires reinforcing a strict separation between the two. The combination of patrimonialism (as an analytical lens) with republicanism (as a normative ambition) calls for expansive concepts of corruption.

The Court’s 2015 decision in ADI 4650 epitomizes this outlook. Striking down corporate campaign donations, Justice Luiz Fux’s leading opinion argued that such contributions undermined the “republican spirit” expected of public officials. He observed that

“there is a real crisis of representation in this country” with members of the political class “often favoring private interests over the public interest.”[7]

His opinion portrayed Brazil’s political finance system as captured by corporate interests, calling for sweeping reform to restore public trust.

This republican framework also shaped the Court’s role in the beginning of Operation Car Wash (Lava Jato), Brazil’s massive criminal anti-corruption campaign. The Court expanded the concept of the crime of bribery by simultaneously relaxing two elements of the quid pro quo paradigm: the explicitness (of the agreement) and specificity (of the official act). Justice Fachin’s leading opinion in AP 1015 (2020) became emblematic of this republican framing, treating any pursuit of private interest in politics as constitutionally suspect. His reasoning treated only ideal‑driven donations as legitimate and left little room for contributions aimed at legislative influence without quid pro quo. That view ignored a more nuanced understanding from ADI 4650—that contributions can aim to influence without constituting bribery.

The tension became clear in 2022, when the same case was reversed, with Justice Gilmar Mendes’ leading opinion warning against criminalizing legitimate contributions aimed at maintaining proper institutional relationships, such as access and dialogue with officeholders––without quid pro quo practices. Justice Mendes noted that corporate contributions were “a valid rule of the democratic game”[8] at the time they were made and argued that receiving “a contribution due to one’s political importance” cannot be considered sufficient to characterize the crime of bribery.[9]

The Supreme Federal Court of Brazil.
The Supreme Federal Court of Brazil, Brasília. Photo by Rob Sinclair via Wikimedia Commons.

Shared Assumptions, Divergent Boundaries

Despite their differences, both courts share a key assumption: elected politicians must exercise some degree of Burkean “best judgment.” Rather than blindly following constituent demands, they must deliberate whether certain private interests align with the public interest.

Where the courts diverge is in their confidence that private interests can be reconciled with the public interest. The U.S. Court views the advancement of private interests as a legitimate—and often valuable—part of democratic life, intervening only when there is clear evidence of quid pro quo bribery. The Brazilian Court, by contrast, has treated private influence as a warning sign, readily expanding legal concepts of corruption, even at the cost of broader judicial discretion and the risk of criminalizing ordinary political activities.

The Risks on Both Sides

Each model carries significant risks.

U.S. Interest Pluralism: The U.S. interest pluralist approach fosters a public perception that politicians overly prioritize private interests without considering the overall benefit of the community. At the same time, by tolerating wide-ranging private influence, this approach risks normalizing the outsized role of wealthy donors and corporations. Critics argue that this fosters “legal corruption”—reciprocal arrangements that fall short of bribery but still erode public trust. The Court’s narrow focus on quid pro quo exchanges leaves little room to address subtler forms of undue influence.

Brazilian Republicanism: Brazil’s expansive anticorruption stance, while rooted in legitimate concerns about patrimonialism, risks judicial overreach. By adopting an enlarged concept of bribery in political finance, courts risk criminalizing ordinary political interactions, either by defining bribery too expansively or by relying on tenuous evidence (such as uncorroborated plea bargains). This can undermine due process and concentrate excessive power in the judiciary, with destabilizing effects on democratic governance.[10]

Both approaches wrestle, in different ways, with the grey zone where private and public interests intersect.

Why This Debate Matters Now

The tension between private interest and public duty is hardly unique to the U.S. or Brazil. Around the world, democracies are confronting similar dilemmas on how to regulate private money in politics.[11] Apex courts are pivotal actors in this struggle. Their rulings not only resolve legal disputes but also shape democratic imagination—defining what “corruption” means, what counts as acceptable political behavior, and where the line between public and private should be drawn. As illiberal leaders increasingly invoke “democracy” to justify power grabs, scrutinizing these judicial conceptions becomes essential.

The U.S. and Brazilian experiences offer contrasting cautionary tales. In the U.S., courts’ narrow corruption framework has enabled unprecedented flows of private money into politics, fuelling perceptions of a system “bought” by elites. In Brazil, courts’ expansive corruption doctrine contributed to historic prosecutions but also to prolonged political instability, including the imprisonment and later release of a former president.[12]

Invitation for Reflection

This comparative perspective is not meant to declare one model superior. Rather, it highlights the stakes of judicial choices in defining democracy itself. As scholars, practitioners, and citizens, we might ask: how much private influence should we accept in democratic politics? Or, more concretely, what kinds of private influence can be regarded as legitimate, and under what circumstances? Engaging more deeply with these questions may help us see more clearly the spectrum of the grey zone between private interests and public duty, and thus set firmer boundaries for democratic practice. These are not merely legal challenges—they are fundamental to how we envision the democratic project.


Statement on artificial intelligence use: I confirm that artificial intelligence tools were employed exclusively for grammar and punctuation checks, as well as for checking the format of citations. The research, ideas, arguments, and writing are entirely my own.


Notes

[1] More broadly, see, e.g., James A. Gardner, “Can Political Parties Be Virtuous?,” Columbia Law Review 100, no. 3 (2000): 667. Related to campaign finance issues, see also Jacob Eisler, “McDonnell and Anti-Corruption’s Last Stand,” UC Davis Law Review 50, no. 4 (2016): 1619.

[2] See Gardner, “Can Political Parties Be Virtuous?”; Eisler, “McDonnell and Anti-Corruption’s Last Stand”.

[3] Citizens United v. Federal Election Commission, 558 U.S. 310, 359–60 (2010).

[4] Citizens United v. Federal Election Commission, 558 U.S. 310, 354–55 (2010).

[5] McDonnell v. United States, 579 U.S. 550, 575 (2016).

[6] See Gardner, “Can Political Parties Be Virtuous?”; Eisler, “McDonnell and Anti-Corruption’s Last Stand”.

[7] STF, ADI 4650, j. 17/09/2015, at 24.

[8] STF, AP 1015, j. 10/11/2020, at 314.

[9] Id. at 307.

[10] For discussions of these issues in the Brazilian context, see Arthur Guerra Filho, “Um País Refém do Conceito de Crime de Corrupção e de Sua Prova,” Revista Direito GV 20 (2024), e2426: 1–30; for discussions in English, see Mariana Mota Prado and Marta R. de Assis Machado, “Using Criminal Law to Fight Corruption: The Potential, Risks, and Limitations of Operation Car Wash (Lava Jato),” American Journal of Comparative Law 69, no. 4 (2021): 834–879.

[11] Arthur Guerra Filho, “Campaign Finance,” in Max Planck Encyclopedia of Comparative Constitutional Law (Oxford: Oxford University Press, 2025), https://oxcon.ouplaw.com/display/10.1093/law-mpeccol/law-mpeccol-e680.

[12] For discussions, see Arthur Guerra Filho, “A Lava Jato, o Financiamento da Política e a Crise da Democracia Constitucional,” Revista Brasileira de Estudos Políticos 129 (2024): 357–392.


About the Author 

Arthur Guerra Filho is a Postdoctoral Fellow at the University of São Paulo (USP) School of Law, where his research has been funded by a FAPESP fellowship, Brazil’s most prestigious postdoctoral award, including support for this post and the article that will follow. He is affiliated with the Constitution, Politics and Institutions (Copi) research group at USP. He will be a Visiting Scholar at Melbourne Law School in 2026. In 2023, he was a Hauser Global Fellow at New York University School of Law (NYU Law). He holds a PhD in Law from King’s College London, an LL.M. from the University of California, Berkeley, and an LL.B. from the Pontifical Catholic University of São Paulo. His research examines constitutional law and election law in comparative perspective. He is the author of “Campaign Finance” in the Max Planck Encyclopedia of Comparative Constitutional Law (Oxford University Press, 2025) and has published in leading journals such as the Journal of Antitrust Enforcement (Oxford University Press), Revista Direito GV (top-tier Brazilian law journal), and the King’s Law Journal (Routledge).


Citation: Arthur Guerra Filho, How Should Elected Politicians Behave? Constitutional Insights from the U.S. and Brazilian Supreme Courts, in: TRAFO – Blog for Transregional Research, 23.09.2025, https://trafo.hypotheses.org/61515


OpenEdition suggests that you cite this post as follows:
Forum Transregionale Studien (September 23, 2025). How Should Elected Politicians Behave? Constitutional Insights from the U.S. and Brazilian Supreme Courts. TRAFO – Blog for Transregional Research. Retrieved January 18, 2026 from https://doi.org/10.58079/14q7l


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