The case, argued by telephone in May because of the coronavirus pandemic, only arose after Congress in 2015 created an exception in the law that allows the automated calls for collection of government debt.

Political consultants and pollsters were among those asking the Supreme Court to strike down the 1991 law that bars them from making robocalls to cellphones as a violation of their free speech rights under the Constitution. The issue was whether, by allowing one kind of speech but not others, the exception made the whole law unconstitutional.

The court threw out the exception for government-debt collection and preserved the broader prohibition.

During arguments, Justice Stephen Breyer got cut off when someone tried calling him. Breyer said after he rejoined the court’s arguments: “The telephone started to ring, and it cut me off the call and I don’t think it was a robocall.”