A person commits the offense of criminal trespass or criminal trespassing by entering or remaining on the property of another—including residential land, agricultural land, recreational land (such as a vehicle park), a building, an aircraft, or an automobile—without consent and if the person (1) had notice that the entry was forbidden, or (2) received notice to depart, but failed to do so.

The definitions and penalties for criminal trespassing vary from state to state and are usually located in a state’s penal or criminal code (statutes).

In Pennsylvania, criminal trespass is defined under the Pennsylvania Consolidated Statutes Title 18, Chapter 35. A person may be charged with criminal trespass if they knowingly enter or remain in any place for which entry or remaining is forbidden, or if they fail to leave after being instructed to do so by the owner or lawful occupant. The law distinguishes between different types of trespassing, such as 'simple trespasser,' 'defiant trespasser,' and 'agricultural trespasser,' each with varying degrees of penalties. The severity of the offense can range from a summary offense to a felony, depending on factors such as the circumstances of the entry, the type of property involved, and whether the trespasser caused any damage. For example, entering a building or occupied structure when it is closed to the public is considered a felony of the third degree, while simply entering a property marked with 'No Trespassing' signs may result in a summary offense or misdemeanor charges. Penalties can include fines, imprisonment, or both, and are more severe for higher degrees of trespass.