(IANAL.) Employment agreements generally are not enforceable when they conflict with the law, AFAIK. The security guard might be required to never open the door

(IANAL.) Employment agreements generally are not enforceable when they conflict with the law, AFAIK. The security guard might be required to never open the door, but when a police officer or court gives them a lawful order to open it, they open it or go to jail. I doubt they could be fired for opening it in that circumstance; your employer cannot require to you violate the law. Another way of looking at it: You can write whatever you want on paper and sign it, but that doesn't make it enforceable. You could sign a document that makes you a slave or puts up your children as collateral for your ISP bill, but those agreements would be scrap paper (or evidence for the prosecutor).