Legal Question in Civil Rights Law in California

It is probably legal, since you have no legitimate expectation of privacy in the parking lot. If the boss records the ocnversation that would be illegal.

Employers may monitor and record phone conversations, emails, computer usage, etc., and may monitor and record by audio/video any employee conduct on company property, and may require inspection of any employee containers, lunch boxes, briefcases, etc. - AS LONG AS the employees are notified of the policy. The courts have even upheld compelled inspections of vehicles ID'ed by sniffer dogs looking for drug or firearms.