Amici curiae often walk a tightrope between offering argument that is supplemental, but also sufficiently within the issues framed by the parties. That tightrope may be even narrower after the Supreme Court issued its decision in United States v. Sineneng-Smith, 140 S.Ct. 1575 (2020), which vacated an order by the Ninth Circuit for violating the party presentation rule.

Under the “party presentation rule,” federal courts are discouraged from considering legal arguments and issues not raised by the parties. Federal courts “rely on the parties to frame the issues for decision and assign to courts the role of neutral arbiter of matters the parties present.”  Greenlaw v. United States, 554 U.S. 237, 243 (2008).

But the party presentation rule comes into tension with federal appellate rules allowing for the filing of briefs by amici curiae. As the advisory committee notes to Federal Rule of Appellate Procedure 29 explain: “[A]n amicus brief is supplemental. It need not address all issues or all facets of a case. It should treat only matter not adequately addressed by the party.” 

In Sineneng-Smith, the Respondent was convicted under a statute making it a federal felony to “encourag[e] or induc[e] an alien to come to, enter, or reside in the United States.” 8 U.S.C. § 1324(a)(1)(A)-(B). Before the district court and in her initial appeal, Respondent argued that the statute did not cover her conduct and that the statute violated the First Amendment as applied to her. She did not present any argument that the statute was facially unconstitutional.

Rather than deciding the case on the issues framed by the parties, the Ninth Circuit panel named three amici and invited argument on whether the statute was overbroad. The amici filed briefs arguing that the statute was indeed overbroad and thus, facially unconstitutional. The Ninth Circuit agreed, reversed Respondent’s conviction, and issued a judgment invalidating the statute.

In a unanimous opinion authored by Justice Ginsburg, the Supreme Court vacated the Ninth Circuit’s judgment, holding that the panel abused its discretion and violated the party presentation rule. The Supreme Court emphasized that an appellate court “is not hidebound by the precise arguments of counsel, but the Ninth Circuit’s radical transformation of this case goes well beyond the pale.” The Supreme Court remanded and instructed the Ninth Circuit to decide the case without consideration of whether the statute was overbroad.

The Supreme Court’s opinion raises many questions for amici in how to navigate crafting arguments on appeal. Does an amici who provides a different theory as to why the lower court erred tempt the appellate court to violate the party presentation rule? Or does a violation only occur when the Court itself conceives of the new argument and invites briefing by amici unprompted? Faced with such a situation, could an appellate court suggest an alternative basis for ruling, and instead of requesting amici brief the issue, request supplemental briefing from the parties?

One could conclude that Sineneng-Smith is an extreme outlier. The Ninth Circuit’s actions were not only unprompted, but the result of its judgment was invalidation of a federal statute. And the differences in the Respondent’s and amici’s arguments were stark; they relied on different constitutional concepts, precedent, and legal analysis. A well-written amicus brief can provide a unique perspective and persuade an appellate court to adopt a particular position. But Sineneng-Smith is an important reminder that amici curiae should not stray too far from the arguments advanced by the parties or else it may cause the court to run afoul of the party presentation rule. And however unlikely a judicial request for briefing on new issues may be in the future, amici may want to carefully consider the expenditure of such efforts in light of Sineneng-Smith. Or, as should be evident from Sineneng-Smith, amici may be comforted in knowing that even if their effort is invalidated, they may have teed up the new arguments for the next, similar case.

Patrick Burns is Senior Counsel with Hanson Bridgett’s Appellate Practice. Patrick focuses on writs and appeals, as well as law and motion in the state and federal courts. A former litigator at a global law firm, Patrick has experience litigating high-stakes disputes. He can be reached at and his blog posts can be read at