"Under traditional law governing naval blockades, key requirements include prior notification, effectiveness, impartial enforcement, and due regard for humanitarian considerations. Accordingly, the legal defensibility of a unilateral blockade of Iranian ports remains highly questionable," Choi said.
He added that maritime blockades are typically considered part of a maritime military conflict and are imposed under the UN Charter and in accordance with UN Security Council sanctions.
"From the standpoint of international law, the action is open to serious legal dispute," he added.
On April 13, the US Navy began blockading all maritime traffic entering and exiting Iranian ports on both sides of the Strait of Hormuz, a waterway that accounts for approximately 20% of the world's oil, petroleum products, and LNG supplies. Washington maintains that non-Iranian vessels are free to transit the strait as long as they do not pay a toll to Tehran.