The Peace and Justice Initiative describes command responsibility as,
“Command or superior responsibility” is often misunderstood. First, it is not a form of objective liability whereby a superior could be held criminally responsible for crimes committed by subordinates of the accused regardless of his conduct and regardless of what his knowledge of these crimes. Nor is it a form of complicity whereby the superior is held criminally responsible for some sort of assistance that he has given to the principal perpetrators. Instead, superior responsibility is a form of responsibility for omission to act: a superior may be held criminally responsible under that doctrine where, despite his awareness of the crimes of subordinates, he culpably fails to fulfill his duties to prevent and punish these crimes.
Are you unsure if President Trump violated the concept of command responsibility when he granted pardons to servicemembers accused of war crimes? Stuart Ford is not sure either as he surveys the question in Has President Trump Committed a War Crime by Pardoning War Criminals? 35 AM. U. INT’L L. REV. 757 (2020).
See also, Brian Finucane, A Commander’s Duty to Punish War Crimes: Past U.S. Recognition. Just Security, 4 December 2020; Jeremy Dunnaback, Command Responsibility: A Small-Unit Leader’s Perspective. 108 NORTHWESTERN U. L. REV. 1385 (2014).