None, according to the Obama administration.

And how much evidence should the government be obliged to possess of an American’s wrongdoing before officially targeting them for killing?

That’s a secret, according to the Obama team.

As part of its war against violent extremism, the Obama administration now claims a right to kill Americans without a trial, without notice, and without any chance for targets to legally object. On May 6, the US government launched a drone attack to try to kill a US citizen in Yemen. The Obama administration alleges that Anwar al-Awlaki, an American born Muslim cleric, helped spark killings at Fort Hood, Texas, and an attempt to blow up a jetliner in 2009. Mr. Awlaki might be a four-star bad guy, but government press releases and background briefings have not previously been sufficient to justify capital punishment. The drone attack failed to terminate Awlaki, though two other people were killed.