We’re now in hour four of Sen. Rand Paul’s filibuster of CIA nominee John Brennan. Paul is being reinforced on the Senate floor by Republican Sens. Mike Lee and Ted Cruz, and Democrat Sen. Ron Wyden, all of whom are giving speeches and engaging in back-and-forth.

At the center of Paul’s objection is the Posse Comitatus Act of 1878, which generally prohibits the federal government from using the military on domestic soil for law enforcement purposes without first passing an act of Congress (and with the exception of the National Guard). Eric Holder said in a recent letter that drone strikes could be ordered against a target on U.S. soil, which Paul argues violates the principle of posse comitatus.

But the Obama Administration isn’t the first to hoe this ground. During the Bush Administration, a legal memo was circulated by White House attorneys that argued, “The president has ample constitutional and statutory authority to deploy the military against international or foreign terrorists operating within the United States.” The document was written by lawyers John Yoo and Robert Delahunty, sent to then-Attorney General Alberto Gonzales, and approved of by Vice President Dick Cheney and his lawyer David Addington. Cheney later argued, citing the memo, that the president could deploy the military against a group of terrorism suspects living in New York, known as the Lackawanna Six. Bush ultimately overruled Cheney and sent in the FBI.

There is, of course, a difference between a military operation and a drone strike. But the principle remains the same. As conservatives by-and-large voice their support for Rand Paul, it’s worth considering how the GOP has shifted since Cheney’s day. It’s also worth considering how elastic the word “conservatism” has become: it includes both Dick Cheney and Rand Paul, opposite poles of a crucial constitutional issue.

Paul’s filibuster represents the Tea Party’s liberty-oriented conservatism at its finest. Take note GOP bosses: this is why we elect men like Paul and Lee. Can you imagine the fearsome Trey Grayson-Bob Bennett tag team fighting tooth-and-nail for our constitutional rights? I’m having difficulty.