Justice;
I was pressed for time when I first responded to your question. I have more time now.
I'm a Director for Security for a large provate corporation. We have an in-house proprietary security force. In the state of Illinois, our security officers have no powers of arrest, search and seizure or detention beyond that of a private person. So, in the state of Illinois, there is no right to search a vehicle for any reason. We must first have the permission of the vehicle's owner - even if a crime involving the vehicle was witnesses by the security officer. In the state of Missouri, that is different. On the premises for which the officer is licensed, they carry the same authority as a sworn officer of the law. Vehicle searches are, however, still normally carried out by permission only.
If you are on a premises that is gated or fenced, the corporation may have the authority to deny the vehicle exit right if they determine a crime has been commited on their property and the evidence is in the vehicle...particularly if theft from the company is suspected. In that case, a voluntary search would be requested first, followed by a call to the authorities. Then it becomes a legal question.l
Regardless, the company must have an established and written policy concerning searching of personal property on company property. Desks, lockers, computers, phones are all open to search. The policy must have been made known to the employee at some point. Either in their employee handbook or during training, or the myriad of forms an employee fills out at the time they are hired. Also, clearly posted notices can suffice in some instances.
It may be that the company has a policy of random searched of lunch boxes or purses either entering or leaving the premises. That is legal. It may pertain to vehicles that are parked on company property as well. In most cases, there is off company parking made available.
In answer to your question, we can't answer you. It varies from state to state, company to company. If the company has a policy against firearms on company property, then undoubtedly they have a policy about searches as well. Do you research.
Dan C