Answer: The best course of action is to contact an experienced employment lawyer. Workplace privacy is an evolving area of the law, as legal rules that are hundreds of years old must adapt to the latest advances in technology. This makes for a rapidly changing legal landscape, best explored with the assistance of a lawyer.
Workplace privacy issues also depend on state laws. For example, some states make it illegal for an employer to film employees secretly; others don't. Some states put limits on an employer's right to require drug tests; others don't. Because your rights will depend, in part, on the laws of your state, you'll want to talk to a local lawyer.