The newspaper quoted unidentified sources who had seen a classified document written last year regarding Muslim cleric Anwar al-Awlaki and the U.S. government's justification in killing him.
The imam was killed Sept. 30 in Yemen by rockets fired by two U.S. drone aircraft, remote-controlled aircraft traditionally operated by the CIA.
The Times said the 50-page classified document contained legal dodges around U.S. anti-assassination policies, human rights, murder and international war positions, which ultimately was approved by President Barack Obama.
The lawyers who wrote the justification said the United States was entitled to target Awlaki because "he was taking part in the war between the United States and al-Qaida" and the government of Yemen was either unwilling or unable to apprehend him.
Awlaki is was a principal suspect in several foiled al-Qaida terror attacks in the United States.