Trespassing in South Carolina

My question involves criminal law for the state of: South Carolina.

Last night, my boyfriend and I were hanging out with two of our friends in a parking lot. (Background info: there is a sonic at the top of the parking lot, but not actually IN the parking lot. Business owners in the parking lot do not mind if people hang out in the parking lot on the weekends as long as there is no littering and no trouble. There are no "no trespassing" signs up, and no signs that say parking for "such and such shop" only). Well while we were hanging out in the parking lot, along with about fifty to seventy five other people just hanging out talking, a police officer comes up to my boyfriend and asks his name then for his ID. He complies and gives the officer his drivers license. The officer then tells him that there is a warrant for his arrest for trespassing (in the parking lot and at sonic)! I could understand if maybe Sonic didn't want him there and called the cops on him, but Sonic does not own the parking lot where we were so I don't get why he was trespassing ON BOTH PROPERTIES. First of all, my boyfriend NEVER got anything in the mail saying he was not allowed to be in that parking lot, and he never got served with trespassing papers. Is this legal?? The officer did not arrest him, but said an officer with the Columbia Police Department would be in touch with him.. If he was not allowed LEGALLY to be in this parking lot, wouldn't he have gotten served papers? And if he is not allowed to be in that parking lot then why is everybody else allowed there? I don't understand. He doesn't cause any trouble. There are plenty of other people in the parking lot starting fights and causing people to go to the hospital with injuries and yet they don't get arrested for trespassing. If someone could clarify this for me I would really appreciate it.

Yes, it's perfectly legal for your boyfriend to be prosecuted for trespassing, regardless of whether anyone else is prosecuted, and regardless of whether "No Trespassing" signs are posted.

I don't have "No Trespassing" signs in my yard, after all, but that doesn't mean I can't call the cops on you for hanging out there without my explicit permission. That parking lot is private property, just like my yard is.

Your boyfriend needs to retain counsel immediately, to negotiate the terms of his surrender. Arrest warrants don't ever go away.

Well he hasn't been arrested or charged with anything yet.. The officer told him he needed to leave so we left immediately. We haven't heard anything else yet. There is an employee at the Sonic I mentioned in my first post that cannot stand my boyfriend and who will do anything to keep him away from there. I can understand if she perhaps put a restraining order on him for sonic specificly but in order for it to take effect my boyfriend would have recieved something in the mail and they would have to have a receipt of him recieving it in order for it to take effect--which he hasn't gotten. It isn't fair for just him to get a warrant for his arrest (if in fact there is one at all--sounds like the cop is going on the employee's word and didn't actually check to see if in fact he was trespassing) and nobody else in the parking lot. I think something fishy is going on and the employee at sonic has it in for him for no reason whatsoever.

UPDATE:: my boyfriend talked to the district manager at sonic and found out that there never was a warrant for his arrest, and never will be. He was not trespassing at all and should feel free to go up there as often as he feels like. The employee that made the bogus call about him trespassing is getting fired, as they have had more complaints about her than any other employee there. Gotta love it when that weight of worrying about whether or not a loved one is going to be arrested is lifted!