I think that when people say that (and I do say that on occasion), it is usually in response to something like abortion, where there is a grey and ill defined area of contention. It is probably an inaccurate use of the word morality.
I've used that phrase when I actually mean, 'you can't legislate your dogmatic beliefs.'
I've used that phrase when I actually mean, 'you can't legislate your dogmatic beliefs.'