Peeping Tom laws—also known as voyeurism laws or invasion of privacy laws—generally make it illegal and a criminal offense to peek into windows or doors on private property to view a person who is fully or partially naked for the purpose of sexual desire or gratification.

Peeping Tom laws vary from state to state and some states require that the victim not realize he or she was being viewed and that the victim had a reasonable expectation of privacy (was in a place where it was reasonable to expect privacy). And some states specifically address the use of unmanned aircraft (drones), cameras, video cameras, and binoculars in connection with such peeping. Some state statutes specifically prohibit peeking into bathrooms, dressing rooms, showers, and baths. And some states characterize this criminal offense as trespassing with the intent to peer or peep.

Peeping Tom laws are located in a state’s statutes—often in the penal or criminal code.

In Illinois, Peeping Tom laws are addressed under the state's criminal statutes, specifically under the Illinois Criminal Code of 2012. The relevant law is 720 ILCS 5/26-4, which prohibits the act of unauthorized video recording and live video transmission. It is illegal to make a video record or transmit live video of another person without their consent in a restroom, tanning bed, tanning salon, locker room, changing room, or a hotel bedroom. This law also covers situations where a person would have a reasonable expectation of privacy and where the recording is done for the purpose of sexual arousal or gratification. Additionally, the use of devices like cameras and drones for such activities can lead to criminal charges. The offense can range from a Class A misdemeanor to a Class 3 felony, depending on the circumstances, such as the age of the person being recorded and whether the offender has prior convictions for the same offense. Illinois law does not specifically use the term 'Peeping Tom,' but the described behaviors fall under the broader category of unauthorized video recording and live video transmission, which encompasses the traditional concept of voyeurism or invasion of privacy.