In my practice as a divorce lawyer, I occasionally have a client tell me that he, or she, has been spying on their spouse, and has some potentially damaging evidence. Spying may be in the form of recording telephone calls, using GPS tracking devices, hacking their spouses cell phone, use of hidden video cameras, hidden tape recorders, or hacking into their spouses social media accounts.
The problem with this "evidence" is that it may be illegal, and the client may have violated federal or state law in the process of gathering the evidence. As such the client may face potential penalties, both civil and possibly criminal as a result. Further the lawyer must consider whether it is ethical and legal to present any such "evidence" in a court proceeding.
As a lawyer, I must consider several issues when a client comes to me with any such spying evidence: Has the client violated federal or state law? Will they need to take the Fifth Amendment if their deposition is taken? Can I use the evidence in court? What are the potential penalties the client may face?
My general advice to these clients is that they should not illegally spy on their spouse, do not record phone or voice without permission, and do not hack into social media accounts, and do not place tracking devices on their spouses car or otherwise.
With regard to social media accounts, if your spouse is "friends" with you on a social media account, or posts messages that are public, any such postings are fair game and may be used as evidence, so long as you do not need to hack into your spouses account to access the postings. Similarly if your spouse sends you text messages or email messages, these are allowable evidence and may be used in court, as are messages left on voice mail or answering machines. However recording your spouse during a phone conversation, or in person, without their knowledge, would not be legal.
Another example of allowable spying is a video security system that does not record voice or sound, and which your spouse is aware of. For example a home video security system that records video only, may be allowable evidence in a court proceeding and would not violate your spouses privacy rights, especially if your spouse is aware of the video security system. If you installed the video system solely to spy on your spouse, and your spouse is totally unaware of the video system, you may have violated your spouses privacy rights. One good way around this issue is a sticker on the front door that clearly states "video recording 24 hours a day on this property" or similar type of warning.
Another fairly safe way to obtain evidence is by hiring a licensed private investigator to do investigation work or surveillance. This type of professional will not gain evidence illegally and will probably be allowed to testify in court.