Private parties cannot file criminal charges. If you are a victim of a crime, such as trespassing, you call the police and they take your statement and gather evidence. The statements and evidence is presented to a court that will determine if they are sufficient to charge the defendant with committing a crime. If the court determines that the statements and evidence is sufficient the court will either issue a summons to the defendant or an arrest warrant.
If the misdemeanor is committed in the presence of a sworn law enforcement officer or a judge, they can skip the step of presenting statements and evidence to a court and issue the summons to appear in court directly to the defendant - this is commonly known as receiving a citation.
In my case of possessing the firearm in the mall, the police officers knew that there were signs posted prohibiting firearms at the mall, but they also knew that I was not committing any criminal act by possessing the firearm in violation of the posted sign and would have no ability to issue a citation. In the case of St. John v. Alamogordo the police detained St. John illegally because he in the theater, just like I in the mall, was not committing any crime.
It is the same basic principal as to whether a crime is being committed or not. Due to the fact that no member of management had notified St. John that his invitation to be on the property had been revoked, he was not guilty of a crime, and therefore there was no justification for the police to detain him.
A sign that says "no guns" or "no skateboarding" or "no running" or "no backpacks" simply is an expression of the desire of the property manager that an object or behavior not be carried or performed on the premises. Failure to adhere to that request, by itself, in no way shape or form constitutes trespassing. The management must notify the person that their invitation to remain on the premises has been revoked and they must be requested to leave the premises.
Seattle Police Department summarizes the requirements for trespassing:
Seattle Trespass Program
and
There are two distinct and separate elements for trespassing:
1. Violating conditions of entry.
2. Notifying that privilege to remain on the premises has been revoked.
Element #1, by itself, does not constitute trespassing. As noted by Seattle Police Department, visitors must be notified by a person with authority that their privilege to remain on the property has been revoked and they must be afforded the opportunity to leave the premises. Only when they refuse to leave is it trespassing.
Again, I am only talking about Washington state. Some states (such as Texas) do have statutes that define carrying a firearm past a properly posted sign as a criminal offense by itself. Some states also have statutes that define any entry without specific authority onto certain premises to automatically be trespassing - railroad right of ways/property is a common one.
