Bank of the United States (9 Wheaton, 865-866), “It is not unusual for a legislative act to involve consequences which are not expressed.  An officer, for example, is ordered to arrest an individual.  It is not necessary, nor is it usual, to say that he shall not be punished for obeying this order.  His security is implied in the order itself.  It is no unusual thing for an act of Congress to imply, without expressing, this very exemption from State control, which is said to be so objectionable in this instance.  The collectors of the revenue, the carriers of the mail, the mint establishment, and all those institutions which are public in their nature, are examples in point.  It has never been doubted that all who are employed in them are protected while in the line of duty; and yet this protection is not expressed in any act of Congress.  It is incidental to, and is implied in, the several acts by which these institutions are created; and is secured to the individuals employed in them by the judicial power alone—­that is, the judicial power is the instrument employed by the Government in administering this security.”

Upon this the Circuit Court observed: 

“If the officers referred to in the preceding passage are to be protected while in the line of their duty, without any special law or statute requiring such protection, the judges of the courts, the principal officers in a department of the Government second to no other, are also to be protected, and their executive subordinates—­the marshals and their deputies—­shielded from harm by the national laws while honestly engaged in protecting the heads of the courts from assassination."[1]

To the position that the preservation of the peace of the State is devolved solely upon the officers of the State, and not in any respect upon the marshals of the United States, the court replied:  This position is already answered by what has been said.  But it is undoubtedly true that it was the imperative duty of the State to preserve the public peace and amply protect the life of Justice Field, but it did not do it, and had the United States relied upon the State to keep the peace as to him—­one of the justices of the highest court—­in relation to matters concerning the performance of his official duties, they would have leaned upon a broken reed.  The result of the efforts to obtain an officer from the State to assist in preserving the peace and protecting him at Lathrop was anything but successful.  The officer of the State at Lathrop, instead of arresting the conspirator of the contemplated murderer, the wife of the deceased, arrested the officer of the United States, assigned by the Government to the special duty of protecting the justice against the very parties, while in the actual prosecution of duties assigned to him, without warrant, thereby leaving his charge without the protection provided by the Government he was serving, at a time when such protection