Is it legal to install cameras and video surveillance in the office and bathrooms?

Your employer may install cameras and other video surveillance in common areas of the workplace without limitation, and in private offices with some restrictions, but never in restrooms or changing areas.

Nowadays, as many a celebrity, criminal suspect, and police officer has learned (often to their regret), video surveillance is near ubiquitous. We can be, and frequently are, videoed almost any place we are. This includes the workplace, with certain limitations. 

The first limitation is in regards to audio recording. The rules are very different between video and audio recording. Audio recording--that is, recording conversations--falls under a state's "wiretapping" laws, even if there is no actual "wiretapping" (intercepting a conversation on a phone call) going on. While states do vary in their wiretapping laws, no state makes audio recording of others' conversations legal unless at least one person involved in the conversation consents or agrees to it--and many states require all parties to the conversation to consent. Since audio recordings of a workplace will frequently pick up conversations where at least some, and sometimes all, of the people speaking have not consented to be recorded, audio recording of your workplace is almost certainly illegal.

The second limitation concerns "reasonable privacy expectations". Basically, whether a reasonable person would legitimately expect to have privacy in that location or context. The law generally finds no privacy expectations in public or common areas: for example, streets, malls, stores, restaurants, or the common areas of workplaces, such as storerooms, loading docks, open plan (or "cubicle") office space, lunchrooms, areas where customers or clients can go, etc. Your employer can freely video record those areas.

As to private offices: remember, that these are really the employer's offices, not the employees'. The employer assigns them to or lets the employees use them, but the employer ultimately controls them. That said, people normally expect privacy in their own private offices--that's why people value private offices, after all. The way the law balances these factors is that there is a reasonable expectation of privacy unless and until the employer tells the employee otherwise. But if the employee, who controls the office space, says that it will record in someone's private office, that defeats or destroys the expectation of privacy.

So the employer cannot secretly or surreptitiously video record in private offices, but if it tells the employee will be video recording in his or her office, then it may do so.

The final factor or consideration is that people may not be videoed in a state of undress or when doing bodily functions. Doing so against someone's will or without their knowledge or consent is criminal: depending on your jurisdiction’s laws and the exact facts, it could even be sexual assault or illegal pornography. Therefore, the employer may never put video cameras in restrooms, locker rooms, changing rooms, breast pumping or breast feeding rooms, and the like.