Q: I was arrested on private property, but since it wasn't "My" land, they didn't need permission or a warrant! Is it true?

A: To complicate the situation, the presence of a residence may also be a factor. I seem to recall a case regarding vacant land and the reasonable expectation of privacy.

But in general, cops are not allowed to invade a home without a warrant or some sort of exigent circumstance.

A: No, the police cannot legally arrest you on private property where you had permission to be without having a warrant or the owner's consent for them to be there. The key issues here are your expectation of privacy and the validity of the police's entry onto the land.

Even though you did not own the land, you still had an expectation of privacy to nap there since the owner gave you explicit permission to be on their property. The police violated that when they entered without consent and arrested you.

The general rule is that absent exigent circumstances, police must have a warrant or permission from the property owner to lawfully enter private property and conduct searches, seizures, or arrests. The fact the land wasn't yours does not negate your granted permission to be there without unlawful intrusion.

Your permission from the owner likely created what is legally known as “standing” to contest the legality of the police's encroachment on the property. You potentially would have solid grounds to legally challenge the arrest through an attorney on the basis of violation of your 4th Amendment protections against unreasonable searches and seizures.

The owner's absence at the time also does not allow police to simply invade at will. At minimum, making an effort to contact the owner for consent would have been reasonably required. So no, the police cannot disregard your rights and permissions simply because it wasn't your own private land. Constitutional safeguards still apply. I would recommend consulting with a criminal defense lawyer to contest the charges.