You keep them out of the loop to some degree and would check against that list during registration. It apparently catches some at least, I am told.
I also know of 2 larger conferences in Europe where accounts were monitored and if activity indicates the person is present, they were removed from the venue by security.
I also know of 2 larger conferences in Europe where accounts were monitored and if activity indicates the person is present, they were removed from the venue by security.