Washington (CNN) -- Federal authorities Wednesday granted two civil liberties groups a license they need in challenging the government's authority to use lethal force against U.S. citizens designated as terrorists.
The action by Treasury Department officials comes just one day after the American Civil Liberties Union and the Center for Constitutional Rights (CCR) filed suit to receive the license they need to go to court. They say it is a first step toward trying to stop the potential targeting of alleged U.S. terrorists abroad.
Regulations give Treasury's Office of Foreign Assets Control authority to license those who provide legal representation to challenge the government.
The ACLU and CCR, which represent the father of wanted Islamic cleric Anwar Al-Awlaki, stressed the urgency of their case because of fears the U.S. government is targeting al-Awlaki for a drone attack in Yemen where he is believed to be hiding.
The ACLU and CCR issued a joint statement saying they "appreciate" the license, but "continue to believe (the Office of Foreign Assets Control) regulations are unconstitutional because they require lawyers who are providing uncompensated legal representation to seek the government's permission before challenging the constitutionality of the government's conduct."
The groups said the Treasury Department indicated the license issued Wednesday can be revoked at any time. The organizations said they would continue to pursue their claim the regulations should be invalidated.
The groups say their ultimate goal is to stop the government's asserted right "to kill American citizens without due process away from conflict zones."
U.S. authorities have targeted suspected terrorists with drone attacks, primarily in Pakistan and Afghanistan. They have identified al-Awlaki, a U.S. citizen, as a "specially designated global terrorist."
Counterterrorism officials say they believe al-Awlaki influenced Maj. Nidal Hasan, accused in the fatal 2009 Fort Hood shootings.
They also accuse al-Awlaki of playing a role in the attempted Christmas day airplane bombing attempt by Abdul Farouk Mutallab near Detroit. And they have indicated Awlaki may also have inspired Faisal Shahzad who has pleaded guilty to federal terrorism charges in the attempted car bombing in Times Square.