It is illegal to spy on anyone’s cell phone in the United States, as of 2015. Users must install software onto the phones they wish to spy on, and the Computer Fraud and Abuse Act makes it illegal to install software on another person’s device without the individual's consent.
Many local jurisdictions have additional laws that add civil and criminal penalties to modifying another individual’s phone to spy on it. Twelve states require consent from both parties of a telephone call to record it.
The sale of spying software is legal in the United States, but sellers often include disclaimers that users should only install the software with the cell phone owner’s knowledge and consent. Individuals who wish to legally track a cell phone can use phone-tracking services that explicitly require consent from the phone’s owner, such as Glympse. Glympse offers a website and mobile app, which require consent from the owner of the tracked phone, and the individual can limit the amount of time that the phone's location is available.
Cell phone owners who suspect they are victims of illegal spying can check for signs of unauthorized phone access, such as higher data usage on monthly bills, shortened battery life, unfamiliar icons and difficulty powering the phone off. Users can remove spy software by restoring the cell phone to factory settings.