Your rule would have to be interestingly drafted to navigate around:
- Abortion
- Risky medical procedures, esp cosmetic ones
- "Bug chasing"
- Euthanasia
The above to one side, I, respectfully, cannot agree with the logic of blanket banning anything preemptively "just to be safe". Consensual (or apparently-consensual) murder is so rare that when/if it comes up - just give the case to a jury to hear the facts in evidence and decide if they believe the consent was valid.
(This is an example of why I believe precedent-based law is superior to legislation-based law)