The Principle of Doing and Allowing is a questionable idea in ethics that states that there is an ethical difference between doing/performing an action and allowing it to happen.
The four police offers involved with the death of George FLoyd were Derek Chauvin, J. Alexander Kueng, Thomas Lane, and Tou Thao. Chauvin pressed his knee into George Floyd's neck for nearly eight minutes with the help of Kueng and Lane while Thao stood by as they killed him.
Chauvin did harm by killing George Floyd and Thao allowed it. According to the Principle of Doing and Allowing, there was a ethical difference between what Chauvin did and what Thao did.