The Supreme Court said Tuesday that part of a federal law that makes it easier to deport immigrants who have been convicted of crimes is too vague to be enforced.

The court's 5-4 decision — in an unusual alignment in which new Justice Neil Gorsuch joined the four liberal justices — concerns a catchall provision of immigration law that defines what makes a crime violent. Conviction for a crime of violence makes deportation "a virtual certainty" for an immigrant, no matter how long he has lived in the United States, Justice Elena Kagan wrote in her opinion for the court.