This reminds me of forbidden substances in the context of sports doping. Some substances are supposed to be illegal but can't be detected yet. I think they are

This reminds me of forbidden substances in the context of sports doping. Some substances are supposed to be illegal but can't be detected yet. I think they are only put on the list once there is an effective test for it. I guess an issue with a honor based system is although nobody can prove you are guilty, you also can't prove you are innocent if someone wrongly accuses you.