The U.S. Supreme Court ruled on Monday that the New York attorney general's office can investigate whether national banks discriminated against minorities seeking mortgages.

The justices overturned part of a ruling by a U.S. appeals court that entirely blocked the state office from investigating or enforcing the fair lending laws against national banks because they are subject instead to federal regulation.

In the court's main split opinion, Justice Antonin Scalia said the state attorney general cannot issue subpoenas, but can bring judicial enforcement actions.