Trespassing is considered any unauthorized entry onto, or refusal to leave, property that belongs to someone else. It covers walking across a fenced yard, staying in a store after being told to leave, entering a restricted military base, and in some circumstances flying a drone low over a neighbor’s house. Depending on the property, your intent, and the state you’re in, the same act can bring a criminal charge, a civil lawsuit for damages, or both.
What Counts as Trespassing
Most trespass situations fall into a few recognizable patterns.
Entering Posted or Enclosed Private Property
The clearest case is walking onto land that’s marked off-limits. “No Trespassing” signs are the familiar example, but about half the states now recognize “purple paint” laws, where vertical purple marks on trees or fence posts carry the same legal weight as a posted sign, so long as the marks meet the state’s rules for size and spacing.
Whether a sign is actually required for a trespass charge depends on the jurisdiction. Some states treat any unauthorized entry as trespass regardless of signage; others let the lack of posted notice work as a defense. The safe assumption is that any fenced or enclosed land is private whether it’s marked or not.
Refusing to Leave After Being Told To
You can become a trespasser on property you entered perfectly legally. If a store manager tells you to leave and you stay, or a homeowner withdraws a guest’s welcome and the guest refuses to go, that person is now trespassing. The notice to leave can be spoken or written, and it doesn’t need to be polite. This is one of the most commonly charged forms of trespass in commercial settings, where retail stores, restaurants, and office buildings all have authority to remove people from their premises.
Entering Government or Military Property
Restricted government land carries some of the heaviest trespass penalties. Federal law makes it a crime to enter a military base, naval station, or Coast Guard installation without authorization, or to return after being ordered to leave, punishable by up to six months in prison, a fine, or both.1Office of the Law Revision Counsel. 18 USC 1382 – Entering Military, Naval, or Coast Guard Property Violating regulations governing national park land carries the same maximum, and trespassing in a national military park to hunt carries between 5 and 30 days imprisonment.2Office of the Law Revision Counsel. 18 USC 1865 – National Park Service
Drones Over Private Property
Traditional trespass requires a physical intrusion, and drones have forced courts to rethink that line. The federal government has exclusive authority over navigable airspace in the United States,3Office of the Law Revision Counsel. 49 USC 40103 – Sovereignty and Use of Airspace and federal regulations set minimum safe altitudes for aircraft at 500 feet over non-congested areas and 1,000 feet over congested areas.4eCFR. 14 CFR 91.119 – Minimum Safe Altitudes General Below those altitudes, property owners have a stronger claim to the airspace directly above their land. Several states have passed laws targeting unauthorized drone surveillance, with penalties ranging from civil fines to misdemeanors when the operator intended to spy on or harass the property owner. The law in this area is still being written.
Criminal Trespass and Civil Trespass Are Different Cases
Trespassing exists in two parallel legal systems, and one act can set both in motion.
Civil trespass is a tort — a private wrong where the property owner sues the trespasser for damages. The standard of proof is lower: the owner only has to show it’s more likely than not that the entry happened. Damages can cover physical harm to the property, disruption to its use, and in some cases emotional distress. For repeated or ongoing trespass, the owner can also seek an injunction barring the trespasser from returning. Violating that order risks contempt of court.
Criminal trespass is prosecuted by the government, and the standard rises to beyond a reasonable doubt. Most criminal trespass statutes also require that the person knowingly entered or remained without permission, which usually takes an accidental entry off the table. Penalties include fines, jail time, or both.
A criminal case doesn’t block a civil lawsuit over the same incident, or the other way around. Both can proceed.
How Intent Changes the Charge
Intent is what separates an honest mistake from a crime. For criminal trespass, prosecutors generally have to prove you knew you weren’t supposed to be there. Courts look at posted signs, fencing, time of day, and what the person was doing to decide whether the entry was knowing. Wandering onto unfenced land because you didn’t realize you’d crossed a property line is a different case from climbing a fence past a “No Trespassing” sign.
Intent also decides whether trespass becomes something worse. If someone enters a building without permission intending to commit a crime inside, the charge often jumps to burglary. Burglary doesn’t require that the intended crime actually happened; the intent at the time of entry is what matters.
In civil cases, intent isn’t required for basic liability. Even an accidental entry can make you responsible for damage you caused. But intent affects what you pay: deliberate, repeated, or malicious trespass can bring punitive damages on top of compensation.
Penalties for Trespassing
Criminal trespass is usually a misdemeanor, and many states grade it by degree based on the type of property and the circumstances. As a rough guide:
- Lower-level trespass, such as entering fenced or posted land or refusing to leave a business, typically carries up to 30 to 90 days in jail and a modest fine.
- Mid-level trespass, such as entering enclosed structures or non-residential buildings, can bring up to six months in jail.
- Higher-level trespass, such as entering someone’s home or trespassing while armed, may be charged as a felony in some states, with potential prison sentences over one year.
Federal trespass has its own ceiling. Unauthorized entry onto a military installation tops out at six months in prison and a fine,1Office of the Law Revision Counsel. 18 USC 1382 – Entering Military, Naval, or Coast Guard Property and violating national park regulations carries the same maximum.2Office of the Law Revision Counsel. 18 USC 1865 – National Park Service Prior offenses, weapons, and the trespasser’s conduct push penalties higher.
Defenses That Can Defeat a Trespass Charge
Not every unauthorized entry results in liability. A few defenses come up again and again.
Consent or an Implied License
If the owner gave permission, there’s no trespass. The consent doesn’t have to be written or formal. An unlocked gate with a visible path to the front door creates what the law calls an implied license: mail carriers, delivery drivers, solicitors, and anyone else approaching along the normal walkway have an implied invitation to knock and leave if no one answers. That license is narrow. It doesn’t cover wandering into the backyard or looking through windows, and a clear “No Solicitors” sign or a locked gate withdraws it.
Necessity
Trespassing to prevent a greater harm is generally excused. Crossing a neighbor’s yard to rescue someone from a burning house is the classic example. The emergency has to be real and immediate, the trespass has to be the only reasonable option, and the harm prevented has to outweigh the harm of the entry. Manufactured emergencies don’t qualify.
Lack of Notice
In states where posted notice is a legal requirement for criminal trespass, the absence of signs, fences, or other warnings can be a complete defense. This is why property owners post signs, paint fence posts, or install fencing in the first place.
A Few Related Rules Worth Knowing
Three issues come up often enough alongside trespass that it’s worth flagging where they fit.
Child trespassers and attractive nuisance. Property owners generally owe trespassers very little, but the rules shift when children are involved. Under the attractive nuisance doctrine, if your property has an artificial condition likely to draw children who can’t appreciate the danger — an unfenced pool, a construction site, abandoned equipment — you may owe a duty to take reasonable precautions. Courts apply the doctrine narrowly and weigh what the owner knew, how serious the risk was, whether children could understand it, and how cheap it would have been to fix.
Using force to remove a trespasser. You can ask a trespasser to leave and call the police if they refuse. Most states also allow reasonable, non-deadly force to remove someone, so long as the force is proportional. Deadly force is a separate category. The castle doctrine permits deadly force against someone who has unlawfully entered a home when the occupant reasonably believes they face imminent death or serious bodily harm, and over half the states have “stand your ground” laws that remove any duty to retreat. Even in those states, deadly force against a trespasser who poses no physical threat is almost never justified. The safer path is to tell the person to leave and call the police.
Adverse possession. Under narrow conditions, a long-term trespasser can eventually claim legal title to the land. The possession has to be open, hostile (meaning without permission), continuous, exclusive, and actual, and it has to last for a statutory period that ranges from as few as 2 years in one state under narrow circumstances to 60 years in another for uncultivated land, with most states falling between 5 and 20. Written permission for someone’s use of your land defeats the “hostile” element and stops the clock before it starts.