Someone caught trespassing on another person's property can face trouble, even possibly a civil lawsuit. But trespass is first and foremost a criminal offense.
While state laws define criminal trespassing somewhat differently, the typical elements of the crime are:
Intent. In order to commit criminal trespass, you must either go onto property knowing that you don't have permission to be there or remain on property after learning that you don't have the right to be there. Accidentally wandering onto someone's land while hiking, for example, typically isn't considered criminal trespass.
Warning or notice required. In many states, laws require there be a warning that you aren't allowed to be on property before you can be convicted for trespassing on the property. While a property owner can directly tell a trespasser to leave the premises, in many states, there are other ways to provide notice that property is off limits. For example, a sign saying "No Trespassing," a fence around the property, or a locked door to the property will do the job.
Specific acts considered trespass. Many states have a general description of trespassing and also outline specific acts that count as the crime. Hunting on someone else's land, cutting down trees without permission, or even tampering with vending machines can be a form of criminal trespass. Entering or remaining in a motor vehicle without the owner's permission is another common form of criminal trespass.
Criminal trespass is related to burglary but is generally considered to be a less serious crime. It's often a misdemeanor or an infraction. In many states, though, it can even be a felony. How seriously the offense will be treated depends on the circumstances of the case.
Generally, criminal laws provide stiffer penalties for illegally entering a residence than for other types of trespass. In Kentucky, for instance, a conviction for entering another person's home without permission can result in up to a year in prison and a fine not to exceed $500. Convictions for most other types of criminal trespass in that state—including illegally entering any type of nonresidential building or enclosed land—carry the possibility of 90 days imprisonment and a fine of up to $250. Other kinds of trespassing in Kentucky are usually violations and can result in fines of no more than $250. (Ky. Rev. Stat. Ann. §§ 511.060, 511.070, 511.080, 532.090, 534.040 (2017).)
As noted above, in addition to criminal charges, a trespasser can face civil liability. Because trespass is a violation of someone's property rights, a property owner can sue a trespasser for money, even if the trespasser didn't cause any harm. (If the trespasser's presence didn't hurt anyone or damage property, though, the plaintiff will likely only be able to recover nominal damages.) Property owners can sometimes sue not only for money, but also for an order putting a stop to a continuing trespass.
Criminal statutes and penalties vary by state. For more information about criminal trespass, or to learn about the laws in your area, consult an experienced criminal defense attorney.