The justices found that the administration exceeded its power in prohibiting the sale and possession of the gun attachments.
The decision is a forceful rejection of one of the government’s few steps to address gun violence, particularly as legislative efforts have stalled in Congress. The challenger was Michael Cargill, a gun shop owner in Texas, backed by the New Civil Liberties Alliance, an advocacy group with financial ties to Charles Koch, a billionaire who has long supported conservative and libertarian causes. The organization primarily targets what it considers unlawful uses of administrative power.