"Believed" itself is not sufficient to meet the Graham v. Connor reasonableness test. He has to show facts and circumstances that would cause a reasonable officer to come to the same conclusion.Probably go nowhere. The K9 handler will say that in the moment he released the dog, he "believed" the suspect was being noncompliant. "That's what was in my head"...therefore it wasn't negligent. It's a version of the Bill Clinton defense; based on the definition of sexual relations I had in my head at the time I made the statements, "I had no reason to believe I was answering any other way but truthfully"...therefore it wasn't perjury.
The union will back him up. Dogs are going to replace the PR-24 baton.