Most likely would be ruled inadmissible evidence in a California court. If this is all they have then they have nothing.
In fact, the the Donal Logue character would more likely find himself jammed up under the law. We have a right to a reasonable expectation of privacy.
You might be right, but what I like about his character is that he doesn't really give a shite. He's going to do it anyway, and break the rules on his side to make it work.
I love when shows set up a sympathetic antagonist. He isn't a Fed who just wants to make a career move by taking down the Sons, he's a renegade who wants to avenge the murder of his sister. It sounds weird, but I hope they don't give us many reasons to not like him.