The Guardian reports: The killing of three US citizens, one a 16-year-old boy, in targeted drone strikes last year were unlawful and violated their constitutional rights by not affording them due process, according to a lawsuit filed by their relatives on Wednesday.

Anwar al-Awlaki, a radical Muslim cleric who was placed on a CIA “kill list” last year, died in a targeted strike in Yemen on 30 September that also killed Samir Khan, an alleged propagandist for al-Qaida, in the Arabian Pensinsula. Al-Awlaki’s teenage son, Abdulrahman, was killed in a separate strike 200 miles away in which six others died two weeks later.

The lawsuit accuses Leon Panetta, the secretary of defence, David Petraeus, the director of the CIA, and two military commanders of authorising and directing unlawful killings. President Barack Obama is not named in the lawsuit: presidents are immune from civil suits arising from their official actions.

The complaint alleges that the deaths are part of a broader programme of deliberate and premeditated killings by the United States, which rely on “vague legal standards, a closed executive process and evidence never presented to the courts”.

The lawsuit has been filed by the American Civil Liberties Union (ACLU) and the Center for Constitutional Rights (CCR) on behalf of Nasser al-Awlaki, the father of Anwar and grandfather of Abdulrahman, and Sarah Khan, the mother of Khan. It aims to force the Obama administration to disclose information about secret decisions behind the killing.