A federal judge has dismissed a lawsuit filed against the US government by the families of three American citizens killed in US drone strikes in Yemen in 2011.
The families of the three, including New Mexico-born militant cleric Anwar al-Awlaki, sued over their deaths, arguing that the killings were illegal.
Judge Rosemary Collyer of the US District Court in Washington threw out the case, but said it raised serious constitutional issues.
"The question presented is whether federal officials can be held personally liable for their roles in drone strikes abroad that target and kill US citizens," Collyer said. "The question raises fundamental issues regarding constitutional principles, and it is not easy to answer."
A lawyer with The American Civil Liberties Union called the decision "deeply troubling."
Nasser al-Awlaki, father of Anwar al-Awlaki, said in a statement he was disappointed in the American justice system and "like any parent or grandparent would, I want answers from the government when it decides to take life, but all I have got so far is secrecy and a refusal even to explain."