In the past I have blogged about using technology to spy on a spouse the potential consequences. I have written about criminal penalties, and civil lawsuits. A recent case, Tinory v. DePierre, Mass.App.Div. No. 14-ADMS-4022 (2015), involved a GPS device planted on a car. This resulted in a claim for trespass. Trespass is normally thought of as the unpermitted, illegal entry onto a person's real property. However, Massachusetts law does allow trespass to personal property. In the Tinory case, the wife in a divorce action hired a private investigator to place a global positioning system device (GPS) on her husband's truck to monitor his whereabouts. This resulted in a lawsuit for trespass because there was an unpermitted, illegal touching of personal property (the truck.)
It is clear that society does not want people to spy on their spouses with technology. While people think that they will get an advantage in a divorce is they get information by spying, it rarely works that way. There are a number of laws with criminal penalties for spying and people may sue in civil court for damages when such spying occurs. In addition, Family Court judges don't want to encourage spying by allowing such evidence to be used.
If you are the victim of electronic spying you should consult a lawyer who can advise you about the law and your options.