The state of California levied a joint bank acct I have with my roommate and took all of his money is that legal, the deposits prove it is his money in the acct

So roommate files a motion in court to request the money be returned, he will need to appear and present the evidence that the money is his.

Was this levy for taxes owed by you? Otherwise it belongs in a different forum.

As long as a person is listed as a joint owner in an account it is legal for a creditor to garnish that account.if they have a court order. If you knew that you had a judgment or debts, then you should not have put your name on the account.

Your friend may be able to recover the funds by going to court and petitioning to vacate the writ of execution by proving you had made no deposits to the account. In the meantime get your name off it.