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 Colorado, upskirting is considered a criminal offense and is addressed under the state's invasion of privacy laws. Specifically, Colorado Revised Statutes section 18-3-405.6 defines 'Invasion of Privacy for Sexual Gratification' as a crime, which includes the act of observing or taking photographs of someone's intimate parts without their consent when the person has a reasonable expectation of privacy. This law applies to situations such as upskirting, where someone takes a photo or video underneath a person's clothing without permission. Depending on the circumstances, such as if the victim is a minor or if the perpetrator has prior offenses, the crime can range from a class 1 misdemeanor to a class 6 felony. Additionally, Colorado's laws against harassment (C.R.S. 18-9-111) may also apply to upskirting behaviors. It's important to note that the interpretation of 'reasonable expectation of privacy' can be complex and may be evaluated on a case-by-case basis by the courts.