Carte blanche to infringe
This isn't an April Fool's Day joke.
In reaching this decision, the Court affirmed the Court of Appeals for the Fourth Circuit and found that the Copyright Remedy Clarification Act of 1990 (CRCA) which stripped States of their immunity to copyright infringement claims was invalid. The CRCA could not rely upon Article I of the U.S Constitution because of Florida Prepaid v. College Savings Bank, 527 U.S. 627 (1999) which held that Congress couldn't justify its attempt to force states into federal court for patent infringement under Article I of the Constitution (opinion at pages 6-10). The CRCA also could not rely upon the 14th Amendment because the CRCA lacked the necessary congruence and proportionality between the constitutional injury to be prevented or remedied and the statutory means adopted (opinion at pages 10-16).
That said, the Court did throw copyright holders a bone. The Court stated that Congress could pass a law based on the 14th Amendment that would survive constitutional scrutiny and strip the States of their immunity (opinion at 16).