Legal Question in Criminal Law in California

Re: first offense, no past records

The search clause no doubt gave them the right to search HIS place, not yours. So, the police' only basis for a search of the premises would be either your consent, or, perhaps, to enter and arrest him if they were in hot pursuit. Otherwise, they should have had an arrest or search warrant. Even then, they would only be entitled to search the immediate area around your friend when they arrested him, or for such things in such places as were stated with particularity in the warrant. They might be able to defend a quick walk through inspection looking for other potential people with weapons, but not a complete search. If you clearly limited the scope of your consent to two rooms, and they found something in a third, the evidence would be illegally obtained against you, and could be suppressed as "fruits of the poison tree". If you are facing criminal charges on this, you should immediately retain a criminal lawyer in your area.

Yes, it is possible you will have a lawsuit against them under 42 USC 1983 for violating your constitutional rights in searching the third room. You may also have additional grounds under various state laws. Consult a tort or civil rights attorney about the possibility of filing a suit.

I would warn, though. Don't be surprised if the police don't claim that you consented to searching the third room as well. Get a copy of the police report as soon as you can.