Public blockade
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
A blockade which is not only established in fact, but is notified, by the government directing it, to other governments ; as distinguished from a simple blockade, which may be established by a naval officer acting upon his own discretion or under direction of superiors, without governmental notification.
The Circassian, 2 Wall. 150, 17 L. Ed. 796.