A team from the amphibious assault ship USS Boxer tows the lifeboat from the Maersk-Alabama to the Boxer, April 13, 2009, after the rescue of Captain Richard Phillips. U.S. Navy photo by Petty Officer 2nd Class Jon Rasmussen

"This government wants Perdicaris alive or Raisuli dead!"

That is how American presidents--in this case, the Teddy Roosevelt administration--used to respond to pirates.

In 1904, New Jersey native Ion Perdicaris was taken hostage by Moroccan bandits. They were led by Mulai Ahmed er Raisuli, who was known as the "Last of the Barbary Pirates."

Even though Perdicaris had moved from Trenton to Greece, Roosevelt believed that an attack on an American anywhere was an attack on Americans everywhere.

The president ordered seven battleships and a contingent of Marines to Morocco and issued the famous instructions demanding the return of Perdicaris. News of Roosevelt's tough stance ensured his renomination at the Republican convention that year.

Roosevelt was only continuing the attitude of past great presidents toward pirates. In 1801, Thomas Jefferson ended the payment of tribute to the Barbary pirates, who preyed on American shipping in the Mediterranean and enslaved U.S. sailors. He sent a naval squadron against the pirates with orders to "chastise their insolence" by "sinking, burning, or destroying their ships & vessels wherever you shall find them." That August, the USS Enterprise fought a three-hour duel with a pirate corsair, killing half its crew, cutting down its masts, throwing its guns overboard, and setting it adrift.

Contrast this with the recent hijacking of the Maersk Alabama. President Obama and, more particularly, the U.S. Navy, are to be praised for the eventual rescue of Capt. Richard Phillips and his American crew. The use of force against the pirates, carried out by the USS Bainbridge and Navy SEAL sharpshooters, displays the virtues of swift and decisive executive action.

The hijacking also shows that the administration's legal and policy confusion over terrorism and piracy has contributed to the very problem at hand. Roosevelt and Jefferson did not worry about whether Congress had authorized their actions against pirates, nor concern themselves with whether pirates deserved better treatment under international law. But the arguments of the far left, consumed by their hatred of Bush and his antiterrorism policies, has come back to haunt the Obama administration.

Under their theory of the war against al-Qaeda, terrorism is really a crime, not an act of war. Terrorists are not illegal combatants (a category recognized by the Supreme Court in past wars and by other nations since Roman times to distinguish between proper soldiers of an enemy state and those who fight outside the laws of war). They do not fall under the Geneva Conventions, not because they choose to fight in violation of the rules of civilized warfare, but because they are just garden-variety criminals. Thus, these criminals cannot be arrested or searched without warrants, cannot be attacked with Predator drones, and must be tried in domestic courts.

The Maersk Alabama incident shows that these arguments have confused the White House's campaign against pirates. The Obama administration seems to think of pirates as criminals, who are to be arrested and hauled back to the United States for trial for the federal crime of piracy.

Obama's order that the Navy could fire only if Phillips were in imminent danger--which limited the sharpshooters to firing only after a pirate pointed an AK-47 at the captain's back--is basically the same rule that applies to police officers pursuing suspects. The FBI was on the scene conducting hostage negotiations.

Treat the pirates as they have consistently been since Roman times, as hostis humani generis, the enemy of all mankind, and the crisis would have been over faster. SEAL sharpshooters should have been able to fire whenever they had a clear shot, regardless of whether Phillips was threatened with imminent harm or death. The same would go for stopping pirate vessels. Rather than let pirates approach peaceful commercial shipping and only then seek to make arrests, our powerful Navy could simply hunt and destroy pirate ships and their land-based support networks "wherever" a commander "shall find them," in Jefferson's words.

But this would require the Obama administration to follow the Bush counterterrorism example by applying the rules of warfare to piracy. This does not mean that the United States cannot resort to its criminal laws, only that conflict with pirates can rise to the level of war and justify the use of military measures, too.

Pirates, of course, do not present as serious a threat to U.S. national security as al-Qaeda or the Taliban (though there are concerns that some of the ransom money going to Somali pirates may find its way to al-Qaeda, which has had significant operations in Somalia). So far, piracy has primarily increased the costs of transporting oil and other goods through the crucial shipping routes of the Indian Ocean, and the dispatch of U.S. naval forces to the area seems to be suppressing the number of successful hijackings.

But the Maersk Alabama shows that piracy threatens a human cost as well, one that can be headed off only through the use of military force applied with a clear vision of piracy as an act of war, pirates as illegal combatants, and the United States as a sovereign nation with the right to clear the seas of this ages-old scourge.

John Yoo is a visiting fellow at AEI.