A lot of criminal cases involve only a single defendant, but lots involve more than one defendant. The case of Bruton v. United States more than fifty years ago dealt with what to do when one or more of those multiple defendants confessed. In a trial involving more than one co-defendant, there are certainly situations where a piece of evidence is admissible against one defendant but not another. In that situation, the solution is typically a jury instruction that the jury is only to consider the evidence against the one defendant but not the others. Bruton said that confessions were different and that the confession could not be admitted in a joint trial involving the confessor and other defendants.
Prosecutors were still reluctant to have more than one trial, and so they attempted to get in the confession with redactions where the names of other defendants on trial were blanked out or replaced. This practice was examined in Gray v. Maryland in 1998 and was found insufficient to protect against the issues identified in Bruton.
In Samia v. United States, issued on Thursday, June 20, 2023, the United States Supreme Court, in a 6-3 decision, seems to back away from the Gray decision. They approved a slightly more robust redaction where the name of the codefendant was replaced with "other person" or "other person he was with." Judge Thomas treats "other person" as being superior to a deleted or blanked name or the word "deleted." He balances the government's interest in having joint trials as outweighing the rights on the individual defendant.
The dissent nails it with a quote from the Bruton decision itself: "The naive assumption that prejudicial effects can be overcome by instructions to the jury, all practicing lawyers know to be unmitigated fiction."