Originally Posted by Sniesk
Doesn't Knox 4th forbids poisons or drugs?
No it forbids unknown
poisons and drugs and complicated devices to be used.
Knox's 4th. It is forbidden for unknown drugs or hard to understand scientific devices to be USED!!
And the Knox's rules are open to interpretation. But Basically it forbids things like time machines, teleportation devices, drugs that cause complicated diseases like "Rokkenjima syndrome". Stuff like that. It has nothing to do with poison or sleeping drugs because those are known to most people.
People can still be poisoned even with Knox's 4th and Maria is most likely poisoned in episode 4.