of their judicial duties, and that such officers are not
within the provisions of that section. To this the court replied that
the language of the section is, "an act done in pursuance of a _law_
of the United States"--not in pursuance of a statute of the United
States; and that the statutes do not present in express terms all the
law of the United States; that their incidents and implications are as
much a part of the law as their express provisions; and that when
they prescribe duties providing for the accomplishment of certain
designated objects, or confer authority in general terms, they carry
with them all the powers essential to effect the ends designed. As
said by Chief Justice Marshall in Osborn v. 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 p