“The proclamation of blockade by the President is, of itself, conclusive evidence that a state of war existed which demanded and authorized recourse to such measure.”
Thus determined the United States Supreme Court in the Prize Cases, settled in 1862 in a split 5-4 decision. The Court examined whether the President had the authority to impose the blockade and call out the militia without the expressed advance approval of the Congress.
The majority agreed that the Constitution gave Congress the power “to provide for calling forth the militia to execute the laws of the Union, suppress insurrections, and repel invasions.” The Court also acknowledged the Executive clause “that the President shall be Commander-in-Chief of the Army and Navy of the United States, and of the militia . . . when called into the actual service of the United States” and that the Executive “shall take care that the laws shall be faithfully executed.”
But the court based its ruling on two subsequent laws adopted by Congress during the early days of the Republic. A February 28, 1795 enactment declared that when the laws of the United States “shall be opposed, or the execution obstructed in any State by combinations too powerful to be suppressed by the course of judicial proceedings,” the President is authorized to call forth the militia “to suppress such combinations.” A March 3, 1807 law granted the President the power to employ the land and naval forces of the United States “for the purpose of suppressing insurrection, and causing the laws to be executed.”
The Court majority concurred that insurrection against a government may or may not culminate in an organized rebellion, “but a civil war always begins by insurrection.”
As a result, the President did not need to await an official declaration of war by the Congress to take action. “If a war be made by a foreign nation, the President is not only authorized but bound to resist force with force,” the majority ruled. Citing the precedence of the Mexican War battles of Pala Alto and Resaca de la Palma, the Court noted they had been fought under Presidential authority and prior to the Congressional declaration of war in 1846. Whether the hostile party be a foreign invader or States organized in rebellion, the majority decreed the President is “bound to accept the challenge without waiting for any special legislative authority.”
Regarding President Lincoln’s response to Fort Sumter, and his call for militia and the blockade to suppress the rebellion, the majority concluded: “The President was bound to meet it in the shape it presented itself, without waiting for Congress to baptize it with a name.”