A rare beast was spotted this week in Washington. An event as rare as the sighting of Big Foot. We actually saw a real filibuster in action.

It was a welcome event – even if it was performed by crazy Sen. Rand Paul – for two reasons. One, because Paul didn’t just threaten a filibuster and then go back to his office and watch ESPN. Paul actually promised to speak as long as his lungs or bladder held out – which turned out to be 12 hours and 52 minutes!

Second reason Rand Paul’s filibuster was such good news? Because it was over U.S. policy on drones, or, rather, the lack of U.S. policy on drones – and timed to coincide with a Senate vote to confirm John Brennan, chief architect of America’s expanded use of drones, as the next director of the CIA.

Only a month ago I posted my last column on this issue, when the Obama administration first declared that, if necessary, it was perfectly legal to use drones to kill American citizens on foreign soil. That assertion, I wrote, was one of the scariest documents – and one of the boldest assertions of executive power – in our lifetime.

Today we’ve seen even a bolder assertion of executive power. Paul took the Senate floor one day after receiving a letter from Attorney General Eric Holder in which he claimed that, while the administration has no intention of doing so, they would be perfectly justified in sending a drone to kill an American citizen – on American soil! – “in an extreme circumstance.” In other words, we no longer have to settle for killing American citizens in another country, we can use drones to kill them right here at home.

Holder’s letter arrived the same day an Alitalia pilot reported spotting what he believed to be a drone in his flight path as he approached New York’s JFK Airport. Whether that aircraft turns out to be a model airplane or drone, such sightings in American skies might soon be commonplace. Drones are being used along our Southern border by U.S. Customs and the Border Patrol, and the FAA has already issued hundreds of drone permits to universities, police departments and other government agencies.

The growing use of drones by domestic agencies is troubling enough, but their expanded and secret use by the Pentagon and CIA poses even more serious questions. The Bureau of Investigative Journalism in the U.K. estimates that some 3,000 people have been killed by American drones in Yemen, Somalia and Pakistan; hundreds were innocent civilians. Two of them, Anwar al-Awlaki and his 16-year-old son, were American citizens.

By what legal authority are we assassinating suspected terrorists in another country, a country with which we are not at war? What senior U.S. official decides who is a legitimate target and who is not? What responsibility do we have for civilians accidentally killed by drones, or simply chalked up as “collateral damage”? What’s the morality of sitting in front of a computer screen at CIA headquarters, playing with a joystick, sending a deadly missile into a compound in Pakistan, killing dozens of men, women and children – and then driving home to eat dinner and watch television with your wife and kids? And, especially, under what possible scenario would our government be authorized to kill U.S. citizens with drone strikes here in America?

The truth is, we don’t know. When it comes to drones, we are, literally, flying blind: dispatching these killing machines with no international law, no domestic law, and no known government guidelines regarding their use. Instead, we make up our own rules as we go along – a flagrant abuse of power we would never accept from another country that decided to fly its drones over the United States.

This may be a tough problem for some Democrats, but it shouldn’t be. Expressing concern about our unlimited use of drones is not a criticism of President Obama. It’s an affirmation of the limits on executive power laid forth in the Constitution and a reminder that even the Authorization for Use of Military Force adopted by Congress after September 11 is not a blank check. Not for torture, under President Bush. Not for drones, under President Obama.

After all, Obama won’t always be in the Oval Office. We may trust him with drones today – but would we trust any future president with the same power?

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