Q: an arrest happened due to trespassing at a store, person never was informed prior by any store personnel not to return

A: Based on the information provided, there are a few potential legal issues to consider under California law:

1. Trespassing: In California, trespassing is defined as willfully entering or remaining on someone else's property without permission (Penal Code 602). However, in this case, the person was not informed prior to the incident that they were not allowed to enter the store. Typically, for a trespassing charge to be valid, the individual must have been given notice beforehand that they are not permitted on the property.

2. Shopkeeper's privilege: In California, store owners and their employees have the right to detain a person suspected of shoplifting for a reasonable amount of time and in a reasonable manner (Penal Code 490.5). However, this privilege requires probable cause to believe that the person has committed theft. In this case, it seems that the person had not been previously charged with petty theft at this store or any other, so the grounds for suspicion may be questionable.

3. Wrongful arrest: If the arrest was made without probable cause or proper justification, it could potentially constitute a wrongful arrest. The fact that the person was arrested for trespassing after being told to leave while shopping, without prior notice of being banned from the store, raises questions about the validity of the arrest.

It's important to note that the specific details and circumstances of the case would need to be examined more closely to determine the legality of the actions taken by the store personnel and the police. The individual in question may want to consult with a criminal defense attorney to discuss their rights and potential defenses based on the particular facts of their case.