A federal court may not toss a conviction because of an error at trial simply based on its own assessment of legal precedent, but rather must also consider a state's own evaluation of the mistake through the lens of a federal law, the U.S. Supreme Court held Thursday in a case involving a Michigan man who was shackled during a murder trial.

Federal courts evaluating a state court's determination that an error at trial was inconsequential to the ultimate verdict not only must evaluate the matter based on legal precedent established by the high court in a 1993 case known as Brecht v. Abrahamson, but must also review the ruling under the Antiterrorism and Effective Death Penalty Act of 1996, according to Thursday's 6-3 ruling.

Based on Brecht, which held that individuals seeking to challenge their convictions must demonstrate that errors at their trials had a "substantial and injurious effect or influence" on the outcome, the Sixth Circuit in June 2020 ordered that Michigan either retry Ervine Davenport or release him, according to Thursday's opinion.

The Supreme Court reversed the Sixth Circuit's determination, ruling that a federal court must also evaluate whether the state's determination that a trial error was inconsequential runs counter to the 1996 law, according to the majority opinion written by Justice Neil Gorsuch.

Under the 1996 law, a federal court may only disturb a state court's conviction after a petitioner has unsuccessfully sought relief should the state court have based its ruling on an "unreasonable determination of the facts," wrote Justice Gorsuch, who quoted the statute.

"We cannot see how the Michigan Court of Appeals acted contrary to or unreasonably applied clearly established federal law," Justice Gorsuch wrote.

Davenport — who prosecutors contended strangled a woman before dumping her body and robbing her home — argued that his civil rights were violated because the jury could see him shackled during his murder trial, which he asserted created a presumption of guilt, according to court documents.

Justice Elena Kagan dissented, writing that Thursday's ruling by a majority of the high court runs counter to recent Supreme Court rulings that only the standard outlined in Brecht needed to be applied, since defendants who met the standard "necessarily" would also meet the test outlined by the 1996 law. Justice Kagan was joined by Justices Stephen Breyer and Sonia Sotomayor.

"Today the court discards those crystal-clear statements, subscribed to on each occasion by every justice," Justice Kagan wrote. "In declaring Brecht insufficient, the majority consigns future habeas courts to a regimen of make-work."

Counsel for Davenport could not be reached for comment on Thursday.

"Today's Supreme Court decision ensures that state court decisions that determine an error at trial was harmless beyond a reasonable doubt are given the deference and respect they are due — not just in Michigan, but across the country," said Michigan Solicitor General Fadwa Hammoud in a statement on Thursday.

Michigan is represented by Fadwa Hammoud of the Michigan Department of Attorney General.

Davenport is represented by Tasha Bahal of WilmerHale.

The case is Brown v. Davenport, case number 20-826, before the Supreme Court of the United States.

--Editing by Peter Rozovsky.