More: The legal hook is the Roberts court's own "history and tradition" test, introduced in the Dobbs decision that overturned Roe. Under that framework, government powers must be grounded in founding-era practice. And the founding era, Kennedy noted, had no national draft, only local militias designed for community defense.

Kennedy acknowledged the current legal landscape cuts against him.

"The question is simple: Is the draft itself constitutional? Under Supreme Court precedent, the answer is yes," wrote Kennedy. "At the same time, the Roberts court has given significantly less weight to precedent than previous courts."

When Secretary of War James Monroe proposed national conscription during the War of 1812, Rep. Daniel Webster called it "not warranted by any provision of the Constitution." Chief Justice Roger Taney later wrote an unpublished opinion agreeing, but no case ever reached the Supreme Court.

"The historical record simply does not support current precedent. Rather, it points to the same conclusion that held for almost the first hundred years of the nation"that the federal government may raise an army, but it may not force anyone to serve in it. And while there is no active draft now, perhaps the transition to automatic registration will inspire some young person to bring the legal challenge that this moment begs," he concluded.