Legal Question in Criminal Law in California

There's no illegal search issue, at least on these facts, because you didn't have a reasonable expectation of privacy -- a police officer has every right to act on information that's in public view such as the tag number and the little serial number on the sticker on a parked car. The police now have automatic license plate reading cameras in their cars that automatically run every plate they pass by, at the rate of hundreds of plates per hour. A bogus sticker on an expired plate might get past a cop, but it won't fool the camera system. You probably have other defenses. This is a serious charge that could result in jail time or, at best, your never being able to get a job again. It would be a good idea for you to obtain private legal representation well in advance of your court date. I'd be happy to talk to you about it.

"Fruit of the poisonous tree" applies when an initial search is illegal. Here, the initial search wasn't really a search at all. That doesn't mean you don't have defenses or other legal remedies, including that you didn't know it was stolen. Either way, you need representation and to discuss this fully with your lawyer.

Nice try. You face misdemeanor criminal charges, for which you would be well advised to hire an attorney. You can fight it. You can raise all your defenses with whatever admissible and credible witnesses, evidence and facts are available for legal arguments. If serious about hiring counsel to do this, feel free to contact me.

The actual charge is forgery of vehicle registration. You could be charged with a felony.