(CNN) -- Two civil rights groups are suing the CIA director, the defense secretary and two military commanders over two covert U.S. strikes that killed three Americans in Yemen last year.
The operations killed radical Muslim cleric Anwar al-Awlaki, his son Abdulrahman al-Awlaki, and Samir Khan, editor of a Jihadist online publication.
The two groups -- the American Civil Liberties Union and the Center for Constitutional Rights -- filed the lawsuit Wednesday on behalf of the parents of Anwar al-Awlaki and Samir Khan.
It claims the strikes that killed the three men violated their constitutional rights because the targeted attacks "rely on vague legal standards, a closed executive process and evidence never presented to the courts," according to the complaint filed in District of Columbia federal court.
"It's about accountability," said Jameel Jaffers, the ACLU deputy director. "If the government is claiming the power, as it seems to be, to kill any American who is deemed to be a national security threat without judicial review of any kind, then we believe the government has an obligation to explain its actions."
But in the case of Anwar al-Awlaki, who was a major figure in al Qaeda in the Arabian Peninsula, the Justice Department has said it is justified.
He was linked to the plot of the so-called "underwear bomber," Umar Farouk AbdulMutallab, and alleged Fort Hood shooter Nidal Hasan, and the Justice Department says there is a legal framework in place that makes going to the courts unnecessary.
"It does not require judicial approval before the president may use force abroad against a senior operational leader of a foreign terrorist organization with which the United States is at war," Attorney General Eric Holder said in a March speech. "Even if that individual happens to be a U.S. citizen."
The legal argument is different for Khan and al-Awlaki's son, both of whose deaths are presumed to be collateral damage in the drone strikes.
Khan was killed in September alongside Anwar al-Awlaki. Abdulrahman al-Awlaki died in a separate drone strike a few weeks later, also in Yemen.
It is unclear whom the U.S. was targeting in that attack and why al-Awlaki's son was near that location.
Jaffers hopes those questions will be answered in court.
Relatives say the terror suspect's son was not affiliated with terrorism.
"I never thought that one day this boy, this nice boy, will be killed by his own government for no wrong he did certainly," his grandfather, Nasser al-Awlaki, said in a video provided to CNN by the ACLU.
Holder said the U.S. takes the death of innocent bystanders into account.
"Under the principle of proportionality, the anticipated collateral damage must not be excessive in relation to the anticipated military advantage," Holder said in March.
The lawsuit against CIA Director David Petraeus, Defense Secretary Leon Panetta and two military officials seeks damages against the four government officials. It does not name a specific dollar amount, only saying "an amount to be determined at trial," according to the complaint.
"It's not about money," Jaffers said. "The main purpose of bringing the lawsuit is to obtain a kind of accountability that can only be obtained in a federal court."
This is the second lawsuit the ACLU has filed on behalf of Nasser al-Awlaki.
In 2010, it filed a suit in federal court trying to prevent the targeting of Anwar al-Awlaki after it was made public that he was on a U.S. government "kill list."
The court dismissed the case a few months later.