practical importance. By the Act of 1807 you may
employ such parts of the land and naval forces as you may judge
necessary for the purpose of causing the laws to be duly executed,
in all cases where it is lawful to use the militia for the same
purpose. By the Act of 1795 the militia may be called forth
'whenever the laws of the United States shall be opposed, or the
execution thereof obstructed, in any State by combinations too
powerful to be suppressed by the ordinary course of Judicial
proceedings, or by the power vested in the marshals.' This imposes
upon the President the sole responsibility of deciding whether the
exigency has arisen which requires the use of military force, and
in proportion to the magnitude of that responsibility will be the
care not to overstep the limits of his legal and just authority.

"The laws referred to in the Act of 1795 are manifestly those which
are administered by the judges, and executed by the ministerial
officers of the courts for the punishment of crime against the
United States, for the protection of rights claimed under the
Federal Constitution and laws, and for the enforcement of such
obligations as come within the cognizance of the Federal Judiciary.
To compel obedience to these laws, the courts have authority to
punish all who obstruct their regular administration, and the
marshals and their deputies have the same powers as sheriffs and
their deputies in the several States in executing the laws of the
States. These are the ordinary means provided for the execution
of the laws; and the whole spirit of our system is opposed to the
employment of any other, except in cases of extreme necessity
arising out of great and unusual combinations against them. Their
agency must continue to be used until their incapacity to cope with
the power opposed to them shall be plainly demonstrated. It is
only upon clear evidence to that effect that a military force can
be called into the field. Even then its operations must be purely
defensive. It can suppress only such combinations as are found
directly opposing the laws and obstructing the execution thereof.
It can do no more than what might and ought to be done by a civil
posse, if a civil posse could be raised large enough to meet the
same opposition. On such occasions, especially, the military power
must be kept in strict subordination to the civil authority, since
it is only in aid of the latter that the former can act at all.

"