Supreme Court strikes down disclosure rules for political donors

The Supreme Court on Thursday struck down a California law that required nonprofits to hand over a list of their biggest donors.

Why it matters: Some campaign-finance advocates have feared the court will begin chipping away at disclosure rules more broadly, making it harder and harder to figure out who’s funding major political causes.

The big picture: In a 6-3 ruling authored by Chief Justice John Roberts, the court said California had subjected donors to the threat of public harassment and intimidation, undermining their First Amendment right to free association.

Background: California requires nonprofit organizations...