Aaron Reitz, who is the U.S. Attorney in the Houston-based Southern District of Texas,  confirmed to Fortune the revival of prize law, or a set of rules allowing for military forces to seize enemy vessels.

“Our national security interests may require the United States military to seize vessels or cargo supporting the enemy during military conflict. If that happens, our federal courts must be ready to adjudicate the disposition of these captured vessels and cargo,” he said in a statement. “Prize law is an ancient body of maritime law—already codified in statute but which we are now reviving—that sets the rules for how seized maritime property is condemned, returned, or disposed of.”

Invoking prize laws would allow U.S. forces to bolster the naval blockade of Iran and recoup costs from the war. The news was first reported by Bloomberg Law.

Prize law contrasts with civil seizure laws that require the U.S. government to identify a statutory violation of a vessel and establish jurisdiction over that violation. It often entails extensive litigation, according to Michael Frevola, a maritime litigation partner at Holland & Knight LLP.

By comparison, prize law does not require a captor to have a warrant or tie a vessel’s seizure to a violation of an existing stature. Rather than law enforcement authorities like the Coast Guard having to seize a vessel under civil seizure laws, the Department of Defense, usually through military force, can seize an enemy vessel instead.

The ‘ancient’ roots of U.S. prize law

Prize laws have existed since the Middle Ages, and have been baked into the U.S. legal canon since the beginning, with the Constitution outlining rules for capturing and confiscating enemy vessels during times of war in its Captures Clause. 

During the 19th century, President Abraham Lincoln used the Prize Act of 1812 to blockade Confederate seaports—an act that was contested and eventually upheld by the Supreme Court. It was most recently invoked during the Spanish-American War, which legitimized the U.S. naval detainment of Spanish vessels as prizes of war.

Reitz did not specify if the Justice Department will invoke the Prize Act of 1812, the Captures Clause, or another law. But the less complicated legal process for capturing an enemy vessel that prize law affords would have clear benefits for the Trump administration.

“There’s definitely a financial interest in being able to sell the oil and being able to to sell the vessel and then just put that money into the coffers of the United States, which is another thing that this administration has shown is a priority,” Raymond Waid, a veteran naval officer and maritime lawyer at Liskow and Lewis, told Fortune. 

Will the Prize Act work in assisting the U.S. in the Iran war?

Legal experts warned that while reviving prize law could in theory expedite the process of seizing Iranian ships, they anticipate ample legal complications that would hamper how effective this legal strategy really is.

For one, there’s the sheer age of the law, which hasn’t been invoked since the Spanish-American War in 1898.

“It’s not like the DOJ has some really veteran Prize Act litigators on their staff,” Frevola quipped. “So we’d have to conduct a séance to wind up getting serious counsel in terms of this.”

The U.S. government will also need to prove that a capture takes place during a war with hostilities that are within congressional and presidential authority. Congress has not declared war against Iran, which may create some grey area around how appropriate prize law would be, and the lack of an official war declaration could also push Congress into getting more involved in a dispute it has largely avoided so far, Waid suggested. 

Allison Luzwick, a maritime lawyer and Frevola’s colleague at Holland & Knight LLP, told Fortune that the U.S. will also likely face litigation about the legality of its blockade and whether it was adequately declared and communicated. This is particularly sensitive for neutral vessels carrying cargo from other states and whether they’re subject to capture.

“There’s going to be arguments about whether or not that vessel is even subject to the blockade, or if they received notice about the blockade, if they intended to run the blockade,” she said.