The Pinkerton liability rule was pronounced by  the Supreme Court of the United States in Pinkerton v. United States, in 1946. Walter and Daniel Pinkerton were brothers who were charged with one count of conspiracy and ten substantive counts under the Internal Revenue Code.
In 1946, the Supreme Court of the United States ruled on the Pinkerton liability rule in the case of Pinkerton v. United States. Walter and Daniel Pinkerton, who were brothers, were charged with one count of conspiracy and ten substantive counts under the Internal Revenue Code.