Updated

Attorneys seeking to overturn the first piracy conviction in a U.S. courtroom in nearly 200 years told a federal appeals panel Tuesday the actions of five Somali men who attacked a Navy warship in waters off Africa did not meet the legal definition of pirates because they did not board the ship or rob it.

The government, however, countered that their violent actions clearly fell within widely accepted international and U.S. law defining piracy.

The hearing was before a three-judge panel of .the 4th U.S. District Court of appeals, which typically issues an opinion several months after arguments

The five defendants, who are serving mandatory life terms for their piracy convictions, were found guilty by a jury in Norfolk in the April 1, 2010, attack on the USS Nicholas. The ship was in the Indian Ocean north of the Seychelles Islands when it was attacked by three men in a skiff, who fired rocket-propelled grenades and raked the ship with AK-47 fire. No sailors were injured in the attack.

During arguments before the three judges, an attorney representing one of the Somalis said the government was using "amorphous" interpretations of international law to make the piracy count stick.

James R. Theuer said the Supreme Court has been clear about a key element of piracy: "It is robbery at sea."

But the government said Congress has embraced the definition of piracy as defined by the law of nations and the evolution of the law over the centuries.

Benjamin L. Hatch, an assistant U.S. attorney, said that piracy definition includes "violent attacks on the high seas" and does not require actual robbery.

The Nicholas, which was part of an international flotilla combating piracy in the seas off Africa, was mistaken by the defendants for a merchant ship because the Navy used a lighting array to disguise the 453-foot (138-meter) warship and attract pirates.

One of the attorneys, David W. Bouchard, referred to the three in the skiff as the "Marx Brothers" for their wayward attack on the Nicholas.

Hatch later bridled at the comparison, saying "This was not the Marx Brothers, but a group of men who shot at U.S. Navy sailors in the dark of night."

Defense attorneys were also appealing several other convictions and questioned whether the five were properly read their Miranda rights once they were captured by the crew of the Nicholas.

Hatch said the men were treated properly and were informed of their right to an attorney. None of the defendants speaks English.

The Nicholas ruling could have an impact beyond that case. Last August, a judge in Norfolk dismissed piracy counts against five defendants accused in an attack on another Navy ship, the USS Ashland. The judge concluded that since the men had not taken control or robbed the ship their actions did not rise to the nearly 200-year-old U.S. Supreme Court definition of piracy.

In the April 10 attack on the Ashland, a 610-foot (185.93-meter) dock landing ship, the ship's 25mm cannons destroyed a skiff, killing one Somali man and injuring several others.

The government appealed the Ashland ruling, but judges on the 4th Circuit set that aside until they heard the Ashland case.

The last U.S. conviction for piracy was in 1819, and involved a foreign vessel. U.S. piracy law was based on that case.

Besides piracy, the five Ashland defendants were convicted of plundering, weapons, assault, explosives and conspiracy charges.