Revisiting which Supreme Court cases are actually the most important

The traditional method of gauging the importance of U.S. Supreme Court cases by simply counting amicus curiae briefs, while insightful, exhibits a notable bias towards civil rights and 'culture war' issues. This article explores the evolution and purpose of amicus briefs, governed by Supreme Court Rule 37, and critically examines the limitations of a raw numerical count as a sole indicator of a case's significance. It proposes a refined approach that considers the qualitative aspects of amicus participation, such as the expertise of the filers and the unique information provided, to offer a more comprehensive and arguably more revealing picture of which cases truly matter to the broader legal landscape and public discourse, beyond immediate ideological contention.

Identifying the most important decisions handed down by the U.S. Supreme Court is a perennial exercise for legal scholars, practitioners, and the public alike. Traditionally, measures of a case's significance have often relied on retrospective analyses, such as the frequency of subsequent citations, inclusion in constitutional law casebooks, or contemporaneous media coverage, particularly front-page features in outlets like The New York Times. While these metrics offer valuable insights, they often suffer from circularity or fail to capture the perceived importance of a case *before* its outcome is known.

An alternative, more forward-looking approach, borrowed from economic theory, suggests that the sheer volume of amicus curiae—or "friend of the court"—briefs filed in a case serves as a credible signal of its perceived importance. The logic posits that the investment of time, money, and reputational capital by numerous knowledgeable parties to file such briefs indicates a widespread belief that the case holds significant implications. However, this raw numerical count has been acknowledged to lean heavily towards cases involving civil rights and contentious "culture war" issues, potentially overlooking other types of cases with profound, albeit less publicized, societal or legal effects. This article delves into the utility and limitations of using amicus brief counts as a measure of case importance and proposes a refinement to provide a more nuanced understanding of the Supreme Court's most impactful decisions.

The concept of an amicus curiae, meaning "friend of the court," has deep historical roots, tracing back to Roman law and subsequently adopted into English common law before making its way into the American legal system. The first recorded instance of an amicus brief in the U.S. Supreme Court occurred in 1823 with Henry Clay's filing in *Green v. Biddle*, 21 U.S. (8 Wheat.) 1 (1823). Initially, amici were often impartial observers providing objective information to the court. However, their role has evolved significantly, with modern amici frequently acting as advocates for particular outcomes, representing diverse interest groups and stakeholders.

In the U.S. Supreme Court, the filing of amicus curiae briefs is governed by Supreme Court Rule 37. This rule explicitly states that an amicus brief "that brings to the attention of the Court relevant matter not already brought to its attention by the parties may be of considerable help to the Court." Conversely, briefs that fail to serve this purpose are deemed to "burden the Court, and its filing is not favored." Rule 37 also outlines procedural requirements, including obtaining consent from the parties or leave of the Court, and specifies filing deadlines. The purpose of these briefs is to assist the Court by offering information, expertise, or insights—whether economic, historical, scientific, sociological, or legal—that extend beyond the arguments presented by the direct litigants, thereby illuminating the broader implications of a potential decision.

The prevalence of amicus briefs has seen an "explosion" since the mid-20th century, particularly after cases like *Mapp v. Ohio*, 367 U.S. 643 (1961), where an amicus brief from the American Civil Liberties Union was notably persuasive. While less than 10% of Supreme Court cases featured amicus briefs between 1920 and 1966, this figure surged to approximately 96-97% of all argued cases in recent terms, such as 2010-2011 and 2019-2020, demonstrating their ubiquitous presence in contemporary Supreme Court litigation.

The proposition that the number of amicus curiae briefs signals a case's importance holds intuitive appeal, reflecting the collective judgment of knowledgeable parties. Indeed, landmark cases often attract a deluge of such filings. For instance, *NFIB v. Sebelius*, 567 U.S. 519 (2012), the constitutional challenge to the Affordable Care Act, drew 136 amicus briefs, a record that was subsequently broken by *Obergefell v. Hodges*, 576 U.S. 644 (2015), the same-sex marriage cases, which garnered 149. More recently, *Masterpiece Cakeshop v. Colorado Civil Rights Commission*, 584 U.S. ___ (2018), a contentious case concerning religious freedom and LGBTQ+ rights, attracted 95 briefs. These examples underscore the method's ability to highlight cases that capture significant public and legal attention.

However, a significant weakness of the raw count method is its inherent bias towards cases that ignite public debate, particularly those touching upon civil rights and "culture war" issues. This can obscure the importance of cases in other areas of law—such as complex regulatory matters, commercial disputes, or federalism questions—that may have profound, long-lasting impacts on various sectors or the structure of government, yet generate fewer, albeit highly specialized, amicus filings. Critics also point out that many amicus briefs are merely "me too" filings, reiterating arguments already made by the parties, and are often ignored by the Court, thus inflating the numerical significance without adding substantive value. As Judge Richard Posner famously noted, many amicus briefs fail to provide unique assistance to the court.

To address these limitations, a refined approach to measuring importance through amicus participation must move beyond a simple quantitative tally. The excerpt hints at considering "whose briefs count," suggesting a qualitative assessment. Research indicates that courts tend to give more weight to briefs from amici with demonstrated expertise, strong institutional legitimacy, or those that offer unique perspectives, specialized data (e.g., scientific, economic, historical), or policy implications not fully explored by the parties. "Scholar briefs" from academics and filings from federal and state governments are frequently cited by the justices, indicating their perceived value. Therefore, a more accurate measure of importance might involve weighting briefs based on the expertise of the filer, the originality of the arguments, or the extent to which they are cited or referenced in judicial opinions.

The influence of amicus briefs on judicial decision-making is empirically supported. The Supreme Court cited amicus briefs in 65% of its opinions during the 2019-2020 term, a record high, demonstrating their role in shaping judicial reasoning. The presence of even a single amicus brief can significantly increase the likelihood of the Court granting certiorari, and a larger number of filings can correlate with a decision favorable to the supported party. However, it is also acknowledged that justices cannot read every brief, relying on their clerks to identify the most relevant submissions. This underscores the importance of quality and distinctiveness over mere quantity, suggesting that a strategic, well-crafted brief from a credible source can be more impactful than numerous redundant filings.

The exercise of identifying the "most important" Supreme Court cases is inherently complex, and while the volume of amicus curiae briefs offers a valuable, forward-looking indicator, its limitations necessitate a more sophisticated approach. Relying solely on a raw count risks overemphasizing ideologically charged cases while potentially overlooking decisions that, though less publicly contentious, fundamentally reshape legal doctrines or societal structures. Practitioners should recognize that the true influence of amicus briefs lies not just in their number, but in their ability to provide unique, expert perspectives and factual information that genuinely assist the Court in its deliberations, as explicitly encouraged by Supreme Court Rule 37.

Moving forward, legal professionals and scholars should advocate for and utilize metrics that incorporate qualitative assessments of amicus participation. This includes analyzing the identity and expertise of amici, the originality and depth of their arguments, and the extent to which their contributions are acknowledged or cited by the Court. By refining our understanding of what constitutes meaningful amicus engagement, we can develop a more accurate and comprehensive framework for identifying the cases that truly matter, both in the immediate legal landscape and for future generations. This nuanced perspective is crucial for strategic litigation, policy advocacy, and a deeper appreciation of the Supreme Court's evolving role in American jurisprudence.