The natural answer is the latter right? Well yes, except the part where you have to hand a criminal whose crime was severe enough to warrant stripping some of his magic a wand and give him enough mental breathing room to perform a complicated, powerful ritual. Some of them are just gonna go along with it, sure, but you only gotta have one high-profile screwup before that kind of a policy is abolished.

Or, you could think strategically for a few minutes then, for example, only give magic wands to wizards for this purpose after they have themselves sworn unbreakable vows that would prevent any misuse.