The Chicago Sun-Times ran a story in mid-November about a criminal trespass case. A man had attempted to enter a woman's home through an unlocked first-floor window. The woman confronted him before he actually entered her home, and he fled. Police arrested him shortly thereafter and, after matching the suspect's fingerprints to fingerprints found at the woman's home, charged him with the misdemeanor of attempted criminal trespass.
What is criminal trespass?
Criminal trespass is an unlawful act committed against a person or property belonging to someone else. Most often, the term is used with regard to real property: A man trespasses when he intentionally walks in someone else's fields, for example, even if he has been warned in writing or in person that his presence on the land is prohibited. The same holds true if the man stays on the property after being told -- again, in writing or in person -- to leave.
Trespass is more than wandering onto someone's property without an invitation. There must be knowledge that the land is off limits.
Criminal trespass in Illinois
The state criminal code breaks trespass into several different categories. There is the most common trespass against real property, along with trespass against a vehicle, against a school building or school grounds, and against state-supported land or a building on state-supported land. All are misdemeanors, with one exception: Trespass against state-supported property with the intent to compromise public safety by delaying transit service or destroying property is a felony.
Again, the prosecutor must prove that the defendant knew of the prohibition and intentionally disregarded it or, at the very least, chose to ignore it. That criminal intent is enough to make even an attempted trespass a crime. The man who tried to go in the woman's window did not enter the premises, but, according to the police, he meant to, so the charge is attempted trespass.
What about the unlocked door or open window?
This is more of a public policy issue than a question of whether the statute discusses open windows or unlocked doors. It is commonly understood that going into someone else's home without permission or without good reason is wrong. It does not make sense to add an exception to accommodate the carelessness of the property owner.
The window was open, but, the law says, that person knew he wasn't supposed to be there.
Illinois Compiled Statutes, 720 ILCS 5/21-1 to 5/21-9 Damage and Trespass to Property, accessed Nov. 20, 2015
Illinois Pattern Jury Instructions-Criminal, Criminal Damage and Trespass, February 2015, via WestlawNext