Federal habeas petitioners must satisfy the prejudice tests in both Brecht and the Antiterrorism and Effective Death Penalty Act in order to obtain relief, the U.S. Supreme Court held April 21 Brown v. Davenport. Satisfying just one test is not enough.

Ervine Davenport was convicted at a jury trial of first-degree murder.
In his direct appeal to the Michigan appellate courts, Davenport claimed his conviction should be set aside because jurors saw him shackled.  The Michigan appellate courts ultimately remanded the case for the trial court to determine whether that error was harmless.
On remand, the trial court conducted an evidentiary hearing at which five jurors testified they saw Davenport in shackles, but that this did not influence their deliberations or verdict.  The remaining seven jurors testified they did not see Davenport shackled.
The trial court ruled the State had met its burden to show the error was harmless, and denied relief.
On appeal of that ruling, Michigan appellate courts affirmed.  They held “the prosecution proved beyond a reasonable doubt that the shackling error did not affect the verdict.”
Davenport then sought federal habeas relief.  
The district court denied relief under AEDPA.  AEDPA requires a petitioner show either that the state court decision was contrary to or an unreasonable application of clearly established federal law set forth by the U.S. Supreme Court, or that the state court decision was an unreasonable determination of the facts presented in the state court proceeding.  
The Sixth Circuit reversed.  
Unlike the district court, the Sixth Circuit did not analyze the case under AEDPA.  Instead, it held the proper test was under Brecht v. Abrahamson, 507 U.S. 619 (1993).
Brecht held that a petitioner must show that an error had a “substantial and injurious effect or influence” on the outcome of his trial.
The Sixth Circuit held Davenport had satisfied his burden under Brecht, and granted relief.
The Supreme Court reversed, in a 6-3 opinion.
            The Brecht standard was adopted before enactment of AEDPA as means of limiting federal habeas review – which, the Court said, had become too broad — and promoting the States’ interest in finality of criminal judgments. 
            Brecht “stressed that undoing a final state-court judgment is an extraordinary remedy reserved for only extreme malfunctions in the state criminal justice system”, the Court said.
Congress enacted AEDPA three years later.
“When Congress supplies a constitutionally valid rule of decision, federal courts must follow it”, the Court said.  “In AEDPA, Congress announced such a rule.”
            “Still, Congress did not wash away everything that came before”, the Court said.  “While AEDPA announced certain new conditions to relief, it did not guarantee relief upon their satisfaction.”
“So even a petitioner who prevails under AEDPA must still today persuade a federal habeas court that law and justice require relief”, the Court said.
“Today, then, a federal court must deny relief to a state habeas petitioner who fails to satisfy either this Court’s equitable precedents or AEDPA”, the Court said. 
“But to grant relief, a court must find that the petitioner has cleared both tests,” the Court held.  “The Sixth Circuit erred when it held Mr. Davenport to just one of these burdens.”
“AEDPA asks whether every fairminded jurist would agree that an error was prejudicial”, the Court said.  “Brechtasks only whether a federal habeas court itself harbors grave doubt about the petitioner’s verdict.”
“A petitioner might be able to prevail under Brecht thanks to favorable circuit case law but still lose under AEDPA because no comparable holding exists in this Court’s precedents”, the Court said.
Even assuming Davenport satisfied the Brecht test, he did not show that Michigan courts had unreasonably applied federal law or unreasonably determined the facts, the Court said.
Justice Kagan dissented, joined by Justices Breyer and Sotomayor.