Some years ago (2003 or so) I was lucky enough to be involved in a case where the court struck down California's AB 1889. That law requires employers receiving state funds not to use them to oppose (or support) union organizing. The California Chamber of Commerce and other groups challenged the law. The district court granted summary judgment in favor of the Chamber and held the law preempted.
On appeal, the Ninth Circuit initially upheld the district court's holding that federal law preempted AB 1889. But, the court then heard the case "en banc" and changed its mind, upholding the California law.
Then, my prior firm was replaced by Supreme Court experts who sought (and obtained!) certiorari review of the decision.
The Supreme Court decided today 7-2 that AB 1889 is preempted by the National Labor Relations Act. That is, California's law impermissibly regulated employers' conduct that is otherwise regulated by the National Labor Relations Act.
This is a very important case for nursing homes and other businesses that receive state funds. The case is Chamber of Commerce v. Brown and the opinion is here.