Yet they can be sued and their and careers ruined if lawyers and mobs get behind those who might be harmed when police do their job.
It brings to the fore the obvious problem with BOTH conventions. Local police and other emergency services can have vacations suspended for the interval, so they have to be there. But what about help from outside departments? Some have already dropped out of Cleveland. Why would any security personnel get involved with either convention if they don't have to? Any amount of money wouldn't be worth the risk.
In CA, it’s by statute.