The justices also grappled with a more technical issue: the standard for issuing a certificate of appealability (COA). In this clip, Chief Justice Roberts, Justice Sotomayor, and Justice Kagan point out that Mr. Buck bore a lower burden of proof to prevail on his request for a COA than he would face to win on the merits of his argument. Specifically, Buck needed to prove only that a reasonable jurist could find that he had made a substantial showing that his constitutional rights had been denied. The justices seemed skeptical of the Fifth Circuit’s holding to the contrary.

Importantly, towards the end of this recording, Justice Kagan points out that the Fifth Circuit denies 60 percent of COA applications yet the neighboring Eleventh Circuit denies only 6 percent of COA applications. This, Justice Kagan argues, is clear evidence that either the Fifth Circuit is too tough or the Eleventh Circuit too lenient. She implies the former is more likely.

Here’s the discussion of the COA’s: