Families of three Americans killed in drone attacks in Yemen last year have sued Defense Secretary Leon Panetta, CIA Director David Petraeus and two top special operations forces commanders.

The airstrikes killed radical Muslim cleric Anwar al-Awlaki, a senior figure in al-Qaeda in the Arabian Peninsula; his 16-year-old son, Abdulrahman; and Samir Khan, the editor of an online, English-language jihadist publication.

The suit contends the targeted killings "violated the Constitution's fundamental guarantee against the deprivation of life without due process of law."

Al-Awlaki was linked to the plot of the so-called underwear bomber, Umar Farouk Abdulmutallab, and U.S. Army Maj. Nidal Hasan, who faces a military trial in a shooting spree that killed 13 and wounded 32 at Fort Hood, Texas, in November 2009.

STORY: Death of al-Qaeda cleric puts wrench in propaganda machine

The American Civil Liberties Union and the Center for Constitutional Rights filed the suit on behalf of the father of Anwar al-Awlaki, who was born in New Mexico, and the mother of Samir Khan, a naturalized citizen who had lived in New York City and North Carolina. Al-Awlaki's son was born in Colorado.

TheNew York Times points out that a federal judge dismissed a bid in 2010 by al-Awlaki's father to halt the Obama administration's effort to kill his son, saying he had no legal standing.

The Times writes that today's lawsuit "may face other procedural impediments before it would reach any substantive ruling on whether the strikes violated the Constitution — or even a public acknowledgment that the United States government did carry them out and an explanation of the evidence and decision-making behind them."

In March, Attorney General Eric Holder defended the Obama administration's policy of targeted assassinations of U.S. citizens linked to terrorism by saying the Constitution does not protect Americans suspected of plotting to kill their countrymen.

STORY: Holder: Constitution doesn't cover terrorists

"Given the nature of how terrorists act and where they tend to hide, it may not always be feasible to capture a U.S. citizen terrorist who presents an imminent threat of violent attack," Holder said in a speech at the Northwestern University law school in Chicago. "In that case, our government has the clear authority to defend the United States with lethal force."

In Sunday's New York Times, national security reporter Scott Shane presented a news analysis headlined "The Moral Case for Drones."

After noting that "most critics of the Obama administration's aggressive use of drones for targeted killing have focused on evidence that they are unintentionally killing innocent civilians," he writes, "It may be a surprise to find that some moral philosophers, political scientists and weapons specialists believe armed, unmanned aircraft offer marked moral advantages over almost any other tool of warfare."

The day after, in Foreign Policy Journal, independent political analyst Jeremy Hammond offered a counterpoint, "The Immoral Case for Drones." He argues that Shane "grievously fails to present" a moral case — "quite the contrary."