A federal judge fired difficult questions at the Obama administration and at civil liberties lawyers on Friday in a court case about whether U.S. citizens abroad targeted in drone strikes can seek compensation from the government.

At a hearing in U.S. District Court in Washington, Judge Rosemary Collyer said she would rule as soon as she could, at least on the preliminary question of whether citizens or their family members have a right to bring a lawsuit.

The U.S. government acknowledged in May that it had killed four Americans in drone strikes in Yemen and Pakistan since 2009 as part of its campaign against al Qaeda and affiliated groups.