This week, at a speech in Chicago, U.S. Attorney General Eric Holder tried to assure Americans that their government takes grave care before deciding to kill one of its citizens. In the Obama administration's first detailed comments explaining targeted drone killings overseas, Holder offered a deliberate accounting of the rationale behind such operations. He needs to go further, however, in providing their legal justification.

Holder's remarks were presumably prompted by the drone attack killing last September of American-born al-Qaida operative Anwar al-Awlaki in Yemen. That operation also killed Samir Khan, 25, an American citizen who lived in Charlotte before leaving for Yemen to produce the al-Qaida magazine, "Inspire."

Khan's parents are still here, and they've said they would like to know why their son wasn't given the due process afforded other U.S. citizens. Regardless of whether Khan and al-Awlaki brought their fates upon themselves, all Americans should want that question answered, too.

Holder went somewhat down that path, saying that a targeted killing of a U.S. citizen would occur only when that citizen poses "an imminent threat of violent attack against the United States," and when "capture is not feasible." He also noted that the administration doesn't need to get a judge's approval before taking action. "The Constitution guarantees due process, not judicial process," he said.

How did administration lawyers arrive at these conclusions? Holder didn't say. The Obama administration has refused to release the Justice Department's legal memorandum on al-Awlaki's killing, and it has opposed lawsuits calling for the release of that information under the Freedom of Information Act.

Holder said rightly that officials need to be nimble when dealing with an imminent terrorist threat. "In this hour of danger, we simply cannot afford to wait until deadly plans are carried out - and we will not," he said. But when dealing with U.S. citizens, his message essentially was: Trust us.

We've been down this road before, specifically after 9/11, when officials in the Bush administration told Americans they should trust the legality and need for enhanced interrogation techniques of terrorists. Later, when Holder's Department of Justice released the Bush Justice Department torture memos, we understood the legal contortions the previous administration had engaged in to defend torture.

For some Americans, any such rationale is fine, now or then, so long as U.S. soil and soldiers are protected. Many among us prefer to keep terrorism - and questions about how we fight it - at a comfortable distance. If two terrorists die in Yemen before pointing their hate our way, what could be wrong about that?

Perhaps nothing. The Obama administration may have sufficient legal justification for targeted killings, but in refusing to cite the underpinnings of its case, it's asking Americans to trust not only this president's choices, but the secret and unchecked decisions of future presidents.

Holder and Obama should release the Justice Department's legal opinion so that Americans can evaluate the reasoning of why and when a country should be allowed to kill one of its own. The president is not only protecting our country, but the Constitution we share. We deserve a fuller explanation when its boundaries are tested.