The limitations to which private investigators are subject depend on the state, but for the most part across all states, private investigators cannot pretend to be members of law enforcement, can’t use illegal methods in the course of their investigations, can’t trespass in a home or business, and can’t place a listening or tracking device without at least the primary party’s consent. In some states, they can wiretap phones if one party is aware, and, likewise, with recording conversations. They also can’t hack people’s emails or private online accounts. Nor can they collect private protected data on their subject without a subpoena. They can only put a GPS tracking device on a car if the owner of the vehicle approves it.