[citation][nom]landerx74[/nom]Why would you go through someone's pictures on their phone? Having those kind of pictures on your phone or anywhere else is sick but there is also that question of privacy and legality. It is possible that now the guy might get off on some technicality.[/citation]
No, because such rules as requiring a warrent, apply only to law enforcement, government employees and people acting at their behest. The bartender is a private citizen, so even though he may have violated the guy's privacy, it is still admissible. If a burglar broke into your house and found your meth lab, then was later picked up some place else, he could rat you out even though his being there was a violation of your expectation of privacy as well as being involved in the commission of a crime.
Please note, I am not a lawyer, but I have researched this a fair amount at the EFF.org website (as well as having taken a few general law classes).