"I do not believe that elected officials can successfully be sued individually for actions taken in office."
That could lead to a terrible Pandora's box. Imagine the President being personally sued for dead soldiers. "That helicopter wasn't safe enough!"
We can win this battle through the election process. Empowering the judiciary is a very, very bad idea.
You can't sue them for negligence in their official capacity. However, if they directly defy the law, then their actions might expose them to liability. Let's take a hypothetical example. Suppose the Mayor orders the police chief to go beat you up for no reason. The police chief does.
Do you think that the Mayor can just say, "I'm Mayor. You can't sue the Mayor?"
I don't think so. There is a limit to which the Mayor is protected while acting in his official capacity.
The question here is whether the Mayor's pariticipation in a City policy which requires the police to disobey federal immigration law (which is undeniably the controlling law) crosses the line. Maybe it does, maybe it doesn't.
In this case, the Mayor also has potential liability in his personal capacity. If I were the lawyer suing him, I'd make sure that I at least mentioned what he did in his official capacity in the court papers. He was way out of line.