A long but interesting paper to read.
http://www.law.harvard.edu/students/...useronline.pdf
I'm particularly fond of this footnote...
(1) Those who propose to change the status quo bear the burden of proving
that change is a good idea; (2) those who propose a new policy bear the burden of
proving that the policy is a good idea; and (3) in a free society those who propose to
abolish a personal liberty passionately valued by millions bear the burden of proving
that abolishment is a good idea.