Upskirting is the act of secretly or surreptitiously photographing underneath a woman’s dress or skirt. Because upskirting often occurs in public places, laws prohibiting the practice have been challenged on the ground that the victim does not have a reasonable expectation of privacy.

Laws regarding upskirting behavior—including photographing or videotaping a person in a bathroom or changing room—vary from state to state. In some states this conduct is prosecuted as a criminal offense under invasion of privacy, voyeurism, unlawful surveillance, surreptitious recording, disorderly conduct, or public lewdness statutes—depending on the state and its current laws.

Upskirting and the related criminal offenses for which upskirting may be prosecuted are located in a state’s statutes—often in the penal or criminal code.

In Illinois, upskirting is considered a criminal offense and is addressed under the state's invasion of privacy laws. Specifically, the Illinois Criminal Code of 2012 prohibits video recording and transmitting live video with a person's undergarments exposed without their consent, which includes upskirting. This act falls under the category of 'unauthorized video recording and live video transmission,' and it is a Class 4 felony. Additionally, if the victim is a minor, the offense is elevated to a Class 3 felony. Illinois law recognizes that even in public places, individuals maintain a reasonable expectation of privacy with respect to the areas of their body covered by undergarments. Therefore, upskirting is illegal regardless of the public or private nature of the setting where it occurs.