Virginia ? A judge on Tuesday dismissed piracy charges against six Somali men accused of attacking a Navy ship off the coast of Africa, concluding the U.S. government failed to make the case their alleged actions amounted to piracy.

The dismissal of the piracy count by U.S. District Judge Raymond A. Jackson tosses the most serious charge against the men, but leaves intact seven other charges related to the alleged April 10 attack on the USS Ashland in the Gulf of Aden. A piracy conviction carries a mandatory life term.

Defense attorneys argued last month that the Ashland defendants did not meet the U.S. legal definition of piracy because they did not take command of and rob the amphibious dock landing ship.

Jackson agreed in his ruling, finding that the government “failed to establish that any unauthorized acts of violence or aggression committed on the high seas constitutes piracy as defined by the law of nations.”

Jackson, who issued the ruling from Norfolk, wrote that the government was attempting to use “an enormously broad standard under a novel construction of the statute” that would contradict a nearly 200-year-old Supreme Court decision, United States v. Smith.