2. As to the degree of the necessity which renders constitutional a law framed to carry a constitutional power into execution, the rule by this decision is,-- "If a certain means to carry into effect any of the powers expressly given by the Constitution to the Government of the Union be an appropriate measure, not prohibited by the Constitution, the degree of its necessity is a question of legislative discretion, not of judicial cognizance." 3. But still more explicitly is the question answered, who is to be the judge of the appropriateness and necessity of the means to be employed, thus:-- "The Government which has a right to do an act, and has imposed upon it the duty of performing that act, must, according to the dictates of reason, be allowed to select the means." Thus, then, the matter stands. The powers to lay and collect taxes, to exercise authority over forts and arsenals of the United States, to suppress insurrection, and various others equally essential, are expressly given by the Constitution to Congress. It is the right and duty of Congress to carry these powers into effect. In case of obstruction or defeat of existing laws framed to that intent, it is the right and duty of Congress to select such means and pass such additional laws as may be necessary and proper to overcome such obstruction and enforce obedience to such laws. In the selection of the means to effect this constitutional object, Congress is the sole judge of their propriety or necessity. These means must not be prohibited by the Constitution; but whether they are the most prudent or the most effectual means, or in what degree they are necessary, are matters over which the Supreme Court has no jurisdiction. As Chief-Justice Marshall has elsewhere in this decision expressed it, for the Supreme Court to undertake to inquire into the degree of their necessity "would be to pass the line which circumscribes the judicial department and to tread on legislative ground." There must, of course, be congruity or relevancy between the power to be enforced and the means proposed to enforce it. While Congress is to judge the degree of necessity or propriety of these means, they must not be such as to be devoid of obvious connection with the object to be attained. In this case, the object to be attained is the enforcement, in the insurrectionary States, of laws without which no government can exist, and the suppression in these States of an insurrection of which the object is the dismemberment of the Union.