Trespass on Land and in Buildings
720 ILCS 5/21-3 — entering after notice, or staying after being told to leave, is a Class B misdemeanor
- Knowingly entering or remaining in a building without lawful authority, which does not cover a building open to the public during its normal hours.
- Entering the land of another after receiving notice that entry is forbidden.
- Remaining on the land of another after receiving notice to depart.
- Using false documents or a false identity to get permission to enter or stay.
Who handles this in Illinois: legal aid programs, lawyer referral and the state offices, listed in the Illinois directory.
Each of those is a Class B misdemeanor. Entering a crop field, livestock area or orchard in a motor vehicle after notice is a Class A misdemeanor.
| How notice is given | What the section says |
|---|---|
| How notice is givenIn person | What the section saysOrally or in writing, including a valid court order |
| How notice is givenPosted | What the section saysA printed or written notice conspicuously posted at the main entrance to the land or the forbidden part |
| How notice is givenPurple marks on trees | What the section saysA vertical line at least 8 inches long, its bottom 3 to 5 feet high, no more than 100 feet apart |
| How notice is givenPurple marks on posts | What the section saysThe top 2 inches capped or marked, no more than 36 feet apart |
An owner who uses purple marks must also give notice in one of the other ways the section lists.
Sources for this section (1)
- 720 ILCS 5/21-3 — Criminal trespass to real property
Legal information, not legal advice. Verified as of October 2026. Applying it to a particular situation is the work of a licensed Illinois attorney.