I think as far as the Ultimate Test goes... many things that a person *has* to do can be deferred until the next opportunity. Just because serial killers tend not to offend in front of police officers, it doesn't mean they don't feel that they *have* to do it, just that they don't *have* to do it right this second. To draw a crass comparison... I don't think I would go for a wee in front of a police officer. That doesn't mean I can 'regulate my behaviour' to the point where I don't have to go for a wee, ever. I can defer my need, but I cannot eliminate it.