[JURIST] The US Supreme Court [official website; JURIST news archive] on Monday ruled [opinion, PDF] 7-1 in United States v. Marcus [Cornell LII backgrounder] that the lower court had misapplied precedent interpreting plain error in an alleged ex post facto violation. The court held that the US Court of Appeals for the Second Circuit had erred in its interpretation of two criteria in finding that a plain error had occurred at trial under Rule 52(b) [text] of the Federal Rules of Criminal Procedure, which would allow the defendant to raise the defense of an ex post facto violation for the first time on appeal. The Second Circuit held [opinion, PDF] that the appropriate standard for plain error review of an asserted ex post facto violation was whether "there is any possibility, no matter how unlikely, that the jury could have convicted based exclusively on pre-enactment conduct." In overturning this standard, Justice Stephen Breyer explained:
[Case law] set[s] forth … that an appellate court may, in its discretion, correct an error not raised at trial only where the appellant demonstrates that (1) there is an "error"; (2) the error is "clear or obvious … "; (3) the error "affected the appellant's substantial rights, which in the ordinary case means" it "affected the outcome of the district court proceedings"; and (4) "the error seriously affect[s] the fairness, integrity or public reputation of judicial proceedings." In our view, the Second Circuit's standard is inconsistent with the third and the fourth criteria set forth in these cases. The third criterion … means that there must be a reasonable probability that the error affected the outcome of the trial. Th[e] standard [used by the Second Circuit] is irreconcilable with our "plain error" precedent. In cases applying this fourth criterion, we have suggested that, in most circumstances, an error that does not affect the jury's verdict does not significantly impugn the "fairness," "integrity," or "public reputation" of the judicial process.
Justice John Paul Stevens filed a dissenting opinion, disagreeing with the majority's conclusion that the appellate court was outside of its discretion:
The trial error at issue in this case undermined the defendant's substantial rights by allowing the jury to convict him on the basis of an incorrect belief that lawful conduct was unlawful. … [T]he Court of Appeals properly exercised its discretion to remedy the error and to order a retrial.
Justice Sonia Sotomayor took no part in the proceedings. She heard the case when it was before the Second Circuit prior to her nomination [JURIST report] to the Supreme Court.
Respondent Glenn Marcus was convicted of sex trafficking and forced labor under the Trafficking Victims Protection Act [text, PDF], enacted in October 2000, for conduct that spanned from January 1999 to October 2001. In February, the Supreme Court heard oral arguments [transcript, PDF; JURIST report] for the case. Counsel for the US government argued that, "[u]nder Rule 52(b), a defendant asserting a forfeited claim of error may prevail only by showing at a minimum a reasonable possibility that the error actually affected the outcome of the case." Counsel for the respondent argued for the application of the Second Circuit's standard.