Luis, althought I agree with you, I should point out that asking the police (or a prosecutor) for a legal opinion is a very bad idea. First off, the police are under no obligation whatsoever to be honest. Second, their understanding of the details of the law is oftentimes somewhat vague.
The best thing to do is to ask a private attorney after paying a retainer fee - that way, at least you can sue them for malpractice after putting their advice into practice blows up in your face.
Actually, this is one of those questions that street cops are well versed in.
I've both owned and run businesses that cater to the general public, and as both owner and manager I've contacted the local police to have individuals removed from the businesses and issued trespassing warrants on many an occasion.