The clock had just struck 1:15 p.m. on Wednesday when the justices, who had been in the courtroom since 10 a.m., finally appeared at a loss of what else to ask U.S. Solicitor General Elizabeth Prelogar about "Chevron deference."

After more than three hours of rapid-fire questioning, over the course of two separate hearings, it seemed like all that could be said had been said about whether to overturn the "foundational" doctrine of administrative law, as Prelogar had called it. 

The silence, however, didn't last long. Prelogar briefly scanned the faces of the justices for follow-up questions before launching back into her defense of Chevron, sparking another round of debate in the cavernous room. It would be nearly 2 p.m. by the time the justices shuffled down from the bench for their regular post-argument lunch together.