In the debate over voter-ID requirements, no one disputes that there is almost no evidence — emphasis on evidence — of in-person voter fraud in this country. People just aren’t showing up at the polls claiming to be someone else. Rather, the dispute is over what conclusion to draw from the absence of evidence. A phony solution in search of a nonexistent problem? That’s how it looks to me, but I recognize that there’s another end to the telescope. During the Supreme Court argument in the Indiana case, Chief Justice John G. Roberts Jr. maintained that the very lack of evidence demonstrated the seriousness of the problem. “It’s a type of fraud that, because it’s fraud, it’s hard to detect,” he said.

When the court went on to affirm Judge Posner’s decision, it was Justice John Paul Stevens who surprised many people by writing the majority opinion. As a lawyer, Justice Stevens had made an early reputation in his hometown of Chicago — ground zero for election fraud — by investigating political corruption. Could that personal history have had anything to do with how he struck the balance in the Indiana case? (Justice Stevens told The Wall Street Journal that he still thinks his opinion was correct based on the information available to the court at the time, but that “as a matter of history,” Justice David H. Souter’s dissenting opinion “was dead right.”)

My Yale Law School colleague Dan Kahan, through his Cultural Cognition Project, uses the lens of psychology to study how people’s group identification and social networks influence their receptivity to scientific information, for example, evidence of climate change. It’s hardly far-fetched to assume that the same dynamic applies to judges across the spectrum of evidentiary questions, even those judges who try to put partisanship aside and think they have succeeded.

Isn’t there such a thing as a good old-fashioned fact that a judge can hang his or her hat on — or is that an outmoded premise in this postmodern world? I’m still scratching my head over Justice Antonin Scalia’s refusal back in June to sign onto Justice Clarence Thomas’s description of the science necessary to understand the patentability of DNA. The patent question was presented in a case about the ownership rights to the test for the gene that puts women at high risk for breast and ovarian cancer. The court’s decision that naturally occurring DNA can’t be patented was unanimous, but Justice Scalia felt the need to add this in a separate opinion: “I join the judgment of the Court, and all of its opinion except Part I-A and some portions of the rest of the opinion going into fine details of molecular biology. I am unable to affirm those details on my own knowledge or even my own belief.” Huh? Justice Scalia either got up on the wrong side of the bed that morning, or is engaging in a meditation on the relationship between knowledge and belief too profound for the mere mortals who write Supreme Court opinions.

Thinking back to the court’s last term, I wonder what the justices make of the revelations that have come to light since the court’s dismissal in February of a case challenging the constitutionality of the government’s foreign intelligence surveillance program. The case, Clapper v. Amnesty International, was brought by human-rights researchers and by lawyers who feared that because their foreign clients were plausible targets of surveillance, their own communications had quite likely been intercepted. The 5-to-4 majority dismissed the case, holding that the plaintiffs’ “speculative chain of possibilities” was insufficient to convey the standing necessary to get into court. As it’s turned out, of course, the actual scale of the surveillance program is outstripping even the wildest speculation on a daily basis (and no, Chancellor Angela Merkel of Germany was not one of the plaintiffs).

When the case was argued on Oct. 29 of last year, Justices Sonia Sotomayor and Ruth Bader Ginsburg pressed the solicitor general, Donald B. Verrilli Jr., on whether the government’s position meant that the program would be forever immune from judicial review, given that potential plaintiffs would never know for certain whether their overseas communications were intercepted. Not so, the solicitor general replied. He said that before using evidence derived from foreign intelligence surveillance in a criminal prosecution, the government would inform the defendant of the source of the information, thus providing standing to challenge the procedure used to collect it.

This was Mr. Verrilli’s belief, but as The Times and others have reported, it was not the policy of the Justice Department’s National Security Division. Spurred by Mr. Verrilli, a battle played out within the department over the summer, leading to a reversal of the non-disclosure policy and, last week, to the government’s first-ever notice to a criminal defendant that it planned to use evidence from a warrantless wiretap.