THE PRIZE CASES
Lincoln proclaimed a blockade of southern ports in April 1861. Congress authorized him to declare a state of insurrection by the Act of July 13, 1861. By the Act of August 6, 1861, Congress retroactively ratified all Lincoln's military action. These cases involved the seizure of vessels bound for Confederate ports prior to July 13, 1861.
Did Lincoln act within his presidential powers defined by Article II when he ordered the seizures absent a declaration of war?
Legal provision: US Const. Art 2
The President had the power to act. A state of civil war existed de facto after the firing on Fort Sumter (April 12, 1861) and the Supreme Court would take this fact into account. Though neither Congress nor the President can declare war against a state of the Union, when states waged war against the United States government, the President was "bound to meet it in the shape it presented itself,without waiting for Congress to baptize it with a name."