A more thorough explanation:

Definition: Bruton error is a violation of a criminal defendant's right to confront their accuser in court. This happens when a confession made by a co-defendant who does not testify in court is used as evidence against the defendant, and the confession is not admissible under any exception to the hearsay rule. Even if the judge instructs the jury to only consider the confession against the co-defendant, there is a high risk that the jury will still use it against the defendant.

Example: Two people are accused of robbing a bank. One of them confesses to the crime and implicates the other person in the confession. The confession is not admissible in court because it violates the defendant's right to confront their accuser. If the confession is still used as evidence against the defendant, it would be a Bruton error.

Explanation: In this example, the confession made by one co-defendant is being used as evidence against the other co-defendant. However, since the co-defendant who made the confession is not testifying in court, the defendant is unable to confront their accuser and challenge the validity of the confession. This violates the defendant's constitutional right to a fair trial.