Oliver Wendell Holmes, Jr.

“ But even the most unquestionable and most universally applicable of state laws, such as those concerning murder, will not be allowed to control the conduct of a marshal of the United States acting under and in pursuance of the laws of the United States. ”

“ It seems to us that the immunity of the instruments of the United States from state control in the performance of their duties extends to a requirements that they desist from performance until they satisfy a state officer upon examination that they are competent for a necessary part of them and pay a fee for permission to go on. ”

“ The cases upon the regulation of interstate commerce can not be relied upon as furnishing an answer. They deal with the conduct of private persons in matters in which the States as well as the general government have an interest and which would be wholly under the control of the States but for the supervening destination and the ultimate purpose of the acts. ”