The Supreme Court ruled in a split decision Friday that a criminal defendant's constitutional rights were not violated when the trial judge allowed prosecutors to admit into evidence the confession of a non-testifying codefendant, since the defendant's name was redacted and jurors were given limiting instructions.

The 6-3 opinion came following oral arguments in late March in the case of Adam Samia, a man convicted of murder for hire.

He and his counsel argued the use of co-defendant David Stillwell's supposedly redacted confession at trial violated the confrontation clause by allowing the jury to glean Samia's identity, even though Samia could not cross-examine Stillwell.

In rejecting Samia's argument, Justice Clarence Thomas wrote in the majority opinion that "historical practice suggests at least that altering a nontestifying codefendant's confession not to name the defendant, coupled with a limiting instruction, was enough to permit the introduction of such confessions at least as an evidentiary matter."

He added, "This historical evidentiary practice is in accord with the law's broader assumption that jurors can be relied upon to follow the trial judge's instructions."

The majority concluded that the confrontation clause "does not provide a freestanding guarantee against the risk of potential prejudice that may arise inferentially in a joint trial."

In Samia's case, "the clause was not violated by the admission of a nontestifying codefendant's confession that did not directly inculpate the defendant and was subject to a proper limiting instruction," Justice Thomas wrote.

Justice Amy Coney Barrett concurred with the majority, but took issue with Justice Thomas citing cases from a "seemingly random time period."

"While history is often important and sometimes dispositive, we should be discriminating in its use. Otherwise, we risk undermining the force of historical arguments when they matter most," she wrote.

Samia's counsel had argued that six circuit courts already allow trial judges to consider the trial's context when deciding if the confession is properly redacted.

However, the Second Circuit, which heard Samia's appeal, considers only whether the confession itself properly removes the co-defendant's name, under the three cases Bruton v. U.S., Richardson v. Marsh and Gray v. Maryland. The U.S. Solicitor General's Office argued these decisions' redaction and anonymization rules go far enough.

Samia was convicted of murder for hire alongside two co-defendants for a 2012 hit on a real estate agent in the Philippines.

Before trial, Stillwell confessed to being the driver and implicated Samia as the gunman.

At trial, Stillwell's confession was redacted to remove references to Samia's name, replacing it with the phrase "the other person" so the jury allegedly could not tell that Stillwell had even named someone when confessing.

But when Stillwell's confession was introduced at trial through the questioning of a U.S. Drug Enforcement Administration investigating agent, prosecutors asked the agent further questions that contextually made it obvious that "other person" referred to Samia, essentially nullifying the redactions, Samia's team said.

In her dissent, Justice Elana Kagan, joined by Justices Sonia Sotomayor and Ketanji Brown Jackson, contended that in allowing redacted confessions, "no matter how obvious the reference to the defendant," the majority was "elevating form over substance" and undermining a "vital constitutional protection for the accused."

"Now, defendants in joint trials will not have the chance to confront some of the most damaging witnesses against them. And a constitutional right once guaranteeing that opportunity will no longer. It will become, in joint trials, a shell of its former self," Justice Kagan wrote.

In a separate dissent, Justice Jackson emphasized that the majority opinion "improperly reframed the constitutional standard that applies to the admission of incriminating testimonial statements of a codefendant during a joint criminal trial."

"In other words, the court has now turned our Bruton cases on their head in a manner that risks undermining a core Sixth Amendment right," she added.

Juries are strongly presumed to follow the instructions given to them. But Bruton created a rare exception to that presumption because of how "devastatingly" prejudicial a co-defendant confession is, Samia's attorney Kannon Shanmugam said.

Over the course of argument, the justices identified an entire range of possible ways to address the question. They could mandate additional limiting instructions to jurors, in conjunction with the way redaction is already done; there could be some kind of mandate for even more-aggressive redactions; or there could even be a rule that in a case with only two defendants, where one implicates the other, the trials must be severed.

"It seems to me, without rewriting [a confession] to make it misleading so that there's no reference to there being another person in the car ... At the end of the day, it boils down to, you just can't try two defendants together if you have a non-testifying defendant and a confession," Justice Amy Coney Barrett said at oral argument.

Shanmugam suggested that the number of defendants is exactly the type of context that courts should be explicitly allowed to consider when deciding whether a confession can come in without violating a defendant's constitutional rights.

As expected with the six-conservative majority, many of whom embrace the doctrine of originalism, history came up as well in arguments. Justice Barrett and others wanted to know how co-defendant confessions were handled in the 1700s and 1800s, around the time of the founding of the country.

According to Shanmugam, around that time, it was not common for co-defendants to be tried together. There also was no such thing as jury instructions as we know them now, he said.

Shanmugam declined to comment.

Samia is represented by Kannon Shanmugam, Elizabeth Norford, William Marks, Brian Lipshutz, Matteo Godi and Morgan Sandhu​ of Paul Weiss Rifkind Wharton & Garrison LLP.

The government is represented by Elizabeth Prelogar, Caroline Flynn, Kenneth Polite Jr. and Kevin Barber of the Solicitor General's Office.

The case is U.S. v. Samia, case number 22-196, in the Supreme Court of the United States.

--Editing by Alyssa Miller.

Update: This story has been updated with more details.