An Obama legal memo wildly stretched the definition of “imminent” to justify the drone attack that killed U.S. citizens Anwar Al-Awlaki and Samir Khan (AP)

A little more than 13 years ago, I got my hands on a confidential Obama administration legal memo that, in retrospect, may have given President Trump all the cover he needed to launch his military attack on Iran this weekend.

At the time, the issue on the table for Obama and his lawyers seemed far removed from the decision Trump just made: to start a war that, in its opening moments, decapitated the leader of a foreign country.

Instead, the question for the Obama crew was a more limited one: What was their basis for launching drone strikes to kill suspected Al Qaeda operatives— even if, as in one notorious case, the operative, Anwar Al-Awlaki, happened to be an American citizen who was born in New Mexico?

The Obama officials’ response was forceful and unapologetic: In a secret Justice Department legal memo— summarized and sent to Congress as a confidential (non-public) “white paper”— they held nothing back, arguing that their lethal drone strikes in Pakistan and Yemen were fully justified because they did not actually constitute “assassinations” theoretically banned by a decades-old executive order.

“A lawful killing in self-defense is not an assassination,” the Obama white paper read. “In the Department’s view, a lethal operation conducted against a U.S. citizen whose conduct poses an imminent threat of violent attack against the United States would be a legitimate act of national self-defense that would not violate the assassination ban.”

Strong language, to be sure. But it was how the administration defined its terms that caused the outrage when I published the previously secret white paper on the NBC News website.

In particular, there was that magic word, “imminent.” In common parlance, imminent has a clear meaning.”Ready to take place: happening soon,” is the way Merriam-Webster defines it.

But the Obama era memo rewrote the definition of imminent to wrench it far beyond anything the dictionary had to say about it. Instead, it refers to what it delicately, if not disingenuously, calls a “broader concept of imminence.”

“The condition that an operational leader present an ‘imminent’ threat of violent attack against the United States does not require the United States to have clear evidence that a specific attack on U.S. persons and interests will take place in the immediate future,” the memo states.

In other words, imminent does not mean there is a plot underway or even that there is intelligence that one is “happening soon.”

Instead, it says, an “informed, high-level” official of the U.S. government may determine that the targeted American has been “recently” involved in “activities” posing a threat of a violent attack and “there is no evidence suggesting that he has renounced or abandoned such activities.”

The memo did not define “recently” or “activities” much less explain whether they too should be injected with a new “broader concept” of meaning.

1984

My publication of this Orwellian rewrite caused a splash. “This is a chilling document,” Jameel Jaffer, then deputy legal counsel for the American Civil Liberties Union told me at the time. “It redefines the word imminence in a way that deprives the word of its ordinary meaning.”

The New York Times, chasing the story in a front page account the next day, also noted it “adopts an elastic definition of an ‘imminent threat’” while calling the memo “the most detailed analysis yet to come into public view regarding the Obama legal team’s views about the lawfulness of killing, without a trial, an American citizen.”

Over time, the controversy over the Obama administration’s drone strikes—and its slippery legal arguments to justify them— faded. As criticism of the strikes intensified, especially after reports of civilian casualties, the administration gradually began to reduce them and impose new restrictions on how they were carried out.

But their legal rationale for them—and in particular, their word games over how to define &...