The Supreme Court ruled 5-3 that if one resident of the house is present and objects, a consent search is not allowed, even if another resident gives consent.
Judge Alito did not participate. Roberts, Scalia and Thomas dissented.
You can access the syllabus here; Justice Souter’s opinion here; Justice John Paul Stevens’ concurring opinion here; Justice Stephen G. Breyer’s concurring opinion here; Chief Justice John G. Roberts, Jr.’s dissenting opinion here; Justice Antonin Scalia’s dissenting opinion here; Justice Clarence Thomas’s dissenting opinion here; and the oral argument transcript here.
Update: Just a reminder. This ruling doesn’t help you if you’re not home and your spouse/roommate give consent for a search. Which is why it’s always a good idea to pick your spouse/roommate carefully, and make sure everybody in the house knows never to consent to a search without a warrant.
And if you ask why you should worry if you don’t have any drugs, I respond: Can you be absolutely sure that none of your friends lost something out of their pocket that went behind the sofa cushions when they visited you? Are you 100% certain that there isn’t a secret compartment or stash in the ceiling left by the previous occupant? Are you looking forward to hiring a lawyer to try to prove you knew nothing about those?