You can be charged with trespassing when you go onto to property that is marked with "No Trespassing" signs or if you stay on property after you've been asked to leave. The "No Trespassing" signs have to be posted clearly and it's not necessary for you to actually see the "No Trespassing" signs to be convicted.
The prosecution will also have to prove that the person who posted the "No Trespassing" signs or told you to leave the property had authority to do so.
If you were forced onto someone else's property, you can't be convicted of trespass. So if someone drove you off the road or chased you onto someone else's property you cannot be convicted of trespass.
If you mistakenly went onto someone else's property, but you should have known you were trespassing, you can still be convicted of trespass. But if you mistakenly went onto someone else's property and the police can't prove that you should have known you were trespassing, you might have a good defense to the charge. To convict you of trespass, the police must prove that you had criminal intent. Criminal intent isn't defined well, but it means more than simply negligently going onto someone else's property.
Another defense to a charge of trespass is if you had permission from one of the property owners to go onto the property. Many times there will be several people who own a piece of property. If one of them gives you authority to be on the property, you can go on the property. But if any of the property owners asks you to leave the property, you must leave.
Trespassing is a Class 1 misdemeanor. That means if you are convicted you could face up to 12 months in jail and a $2,500 fine. It is hard to imagine a case where someone would be a maximum punishment for trespass. In fact, the most common punishment is a fine and a court order to not go onto the property again.
Even though you are probably not going to jail if you are convicted of trespass, it is important to consult with an attorney because there are ways to defend a trespassing charge. Also, because trespass is a Class 1 misdemeanor, it will stay on your criminal record forever if you are convicted. There is no way to have a trespassing charge removed from your record if you are convicted.
If you've been charged with trespass, please call me for a free consultation. You should at least make sure that you understand the charge and whether you have any possible defenses.