It’s also possible that Roberts appears more liberal because, as the chief justice, he has an incentive to join the majority in cases where his vote alone cannot change the decision; this tactic allows him to influence decisions he doesn’t fully agree with, rather than simply dissenting. (The chief justice assigns which justice will write the opinion for whichever group he votes with, so he can indirectly shape a ruling by assigning the opinion to himself or a justice sympathetic to his views.)

There is one would-be justice among the federal appeals judges on Trump’s shortlist who would scoop the median-voter title from Roberts, at least as measured by Judicial Common Space scores — and that’s Thomas Hardiman, a judge who serves on the 3rd U.S. Circuit Court of Appeals.