The Supreme Court ruled Tuesday that a criminal suspect must explicitly invoke the right to remain silent during a police interrogation, a decision that dissenting liberal justices said turns the protections of a Miranda warning “upside down.”

The court ruled 5 to 4 that a Michigan defendant who incriminated himself in a fatal shooting after nearly three hours of questioning thus gave up his right to silence, and the statement could be used against him at trial.

“Where the prosecution shows that a Miranda warning was given and that it was understood by the accused, an accused’s uncoerced statement establishes an implied waiver of the right to remain silent,” Justice Anthony M. Kennedy wrote for the court’s conservatives.

In a separate case, the justices unanimously agreed that a former prime minister of Somalia who now lives in Fairfax County may be sued in U.S. courts by fellow countrymen who claim he oversaw killings and torture in their former home. Mohamed Ali Samantar was part of the country’s ruling government in the 1980s and early 1990s.

In the case about Miranda rights, suspect Van Chester Thompkins remained mostly silent for three hours of interrogation after reading and being told of his rights to remain silent and have an attorney. He neither acknowledged that he was willing to talk nor that he wanted questioning to stop.

But detectives persisted in what one called mostly a “monologue” until asking Thompkins whether he believed in God. When asked, “Do you pray to God to forgive you for shooting that boy down?” Thompkins looked away and answered, “Yes.”

The statement was used against him, and Thompkins was convicted of killing Samuel Morris outside a strip mall in Southfield, Mich.

The U.S. Court of Appeals for the 6th Circuit said that Thompkins’s silence for two hours and 45 minutes of the interrogation “offered a clear and unequivocal message to the officers: Thompkins did not wish to waive his rights.”

But Kennedy said it was not clear enough. “If Thompkins wanted to remain silent, he could have said nothing in response to (the detective’s) questions, or he could have unambiguously involved his Miranda rights and ended the interrogation,” wrote Kennedy, who was joined by Chief Justice John G. Roberts Jr. and Justices Antonin Scalia, Clarence Thomas and Samuel A. Alito Jr. “The fact that Thompkins made a statement about three hours after receiving a Miranda warning does not overcome the fact that he engaged in a course of conduct indicating waiver.”

Kennedy said the court’s new rule — in the case of Berghuis v. Thompkins — was an extension of the logic in a previous case that said a suspect must affirmatively assert his right to counsel.

But Justice Sonia Sotomayor, in the sharpest dissent of her young career on the court, accused the majority of casting aside judicial restraint and creating a rule that marks “a substantial retreat from the protection against compelled self-incrimination” that Miranda established more than 40 years ago.

“Today’s decision turns Miranda upside down,” wrote Sotomayor. “Criminal suspects must now unambiguously invoke their right to remain silent, which, counterintuitively, requires them to speak.” She was joined by Justices John Paul Stevens, Ruth Bader Ginsburg and Stephen G. Breyer.

In the case of Samantar v. Yousef, the court rejected claims by the former prime minister and defense minister that he is entitled to immunity under the Foreign Sovereign Immunities Act. That act protecting “foreign states” from lawsuits does not include individuals, the court ruled.

The court said its finding is narrow, but that a lawsuit filed by members of the Isaaq clan, which alleges acts of detention, torture and murder, can go forward.

“Whether petitioner (Samantar) may be entitled to immunity under common law, and whether he may have other valid defenses to the grave charges against him, are matters to be addressed” by lower courts, Stevens wrote .

-- Robert Barnes