Yeah, that just happened...

 The NLJ's article Calling Justice Breyer: A Court Interrupted, begins:

When the late Supreme Court Justice Robert Jackson wrote in 1953 that justices are infallible “only because we are final,” he did not have cellphones in mind.
Justice Stephen Breyer proved Tuesday that justices are in fact fallible after his cellphone went off during an oral argument.

The faint music of Breyer’s phone introduced a never-heard-of sound into the hallowed court chamber. Bringing electronics of any kind into the court is forbidden, and zealous court police scan entering spectators for errant devices. They are skeptical even of a watch-like Fitbit Blaze, fearing it could record or broadcast something.

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Breyer is not the only person who wears a black robe to work to make this mistake. In 2015, an Ohio judge who was a stickler about cellphones in court held himself in contempt when his device started broadcasting bagpipe music. He fined himself $25.