On Monday, the Supreme Court heard arguments in two different class actions, united by a common problem.

The first, Comcast Corp. v. Behrend, asked whether a trial court should hold plaintiffs to the Daubert standard for expert testimony at class certification, a question that has divided federal circuits for several years. Due in part to a difficult record below (Comcast had not actually registered a Daubert objection), the Justices argued back and forth about whether there was an issue to decide at all, and, if so, what it was. At one point, Justice Kagan remakes in frustration:

I