Twenty years ago Wednesday night, Mark MacPhail, an off-duty Savannah, Georgia, police officer moonlighting as a security guard, was shot to death in a dark parking lot. MacPhail had tried to come to the aid of a homeless man who was being pistol-whipped by a local thug named Sylvester Coles.

Two years later, after what Justice Antonin Scalia described this week as a “full and fair trial,” Troy Davis was convicted of murdering MacPhail and sentenced to death. The evidence at that trial consisted of nine eyewitnesses who claimed Davis shot MacPhail (Davis had been inside a nearby pool hall and was part of a crowd that came out of the hall in response to the commotion in the parking lot where Coles was beating the homeless man).

• Alan Dershowitz: Scalia's Catholic Betrayal The prosecution’s star witness was none other than Coles himself. No physical evidence tied Davis to the crime—the gun was never recovered—and in the years since Davis’ conviction, seven of the eight other eyewitnesses who claimed to have seen Davis shoot MacPhail have signed sworn affidavits recanting their claims. Several now claim Coles was the killer and that they were coerced by police threats into testifying against Davis.

In retrospect, the case against Davis, which wasn’t strong to begin with, has almost completely fallen apart. But Davis has a big problem: As an exasperated Scalia explained in his dissent from Monday’s extraordinarily unusual Supreme Court order directing a federal court to hold an evidentiary hearing on Davis’ claims, there’s nothing illegal about what has happened, and continues to happen, to Troy Davis. (The order is unusual because the court almost never entertains direct appeals by defendants in Davis’ situation.)

Judges of this type like these sorts of cases because they demonstrate that law is a supposedly nonpolitical and intellectually rigorous practice, rather than a touchy-feely exercise in doing what strikes the judge as the right thing.

“This court,” Scalia pointed out, “has never held that the Constitution forbids the execution of a convicted defendant who has had a full and fair trial but is later able to convince a court that he is ‘actually’ innocent.”

Scalia takes the position that, from a legal perspective, it no longer makes the slightest difference whether Davis is innocent of the murder he was convicted of committing, and for which, in all likelihood, he will be executed. If a defendant got a fair trial in state court, there’s nothing the federal court can do, Scalia argues, to reverse that verdict—even if new evidence comes to light that convinces the court to a moral certainty that the defendant is innocent.

Scalia represents an extreme example of a certain kind of judge that positively revels in coming to conclusions that are morally revolting but “legally” sound. Judges of this type like these sorts of cases because they demonstrate that law is a supposedly nonpolitical and intellectually rigorous practice, rather than a touchy-feely exercise in doing what strikes the judge as the right thing.

What, after all, could be more nonpolitical and intellectually rigorous than executing an innocent man, simply because “the law” requires that result? In a perverse way, such bloody logic is a kind of advertisement for the supposed objectivity of the legal system, since we can assume that no sane decision maker would reach such a decision voluntarily. (The great legal historian Douglas Hay explained the 18th-century English practice of sometimes acquitting obviously guilty men on absurd procedural technicalities, such as incorrectly calling the defendant a “farmer” instead of a “yeoman,” in similar terms: “When the ruling class acquitted men on such technicalities they helped embody a belief in the disembodied justice of the law in the minds of all who watched. In short the law’s absurd formalism was part of its strength as ideology.”)

Indeed, I get a certain morbid amusement from the gasps of horror some of my fellow liberal legal colleagues emit when they read something like Scalia’s dissent in the Davis case. “Surely he can’t mean that it’s constitutional to execute an innocent man!” they exclaim.

Oh, but he does mean that. After all, Davis does appear to have gotten what counts as a “fair” trial in our legal system. That he was a 20-year-old poor black man in a state with a horribly underfunded public defender system, and therefore he received a vastly inferior defense to that which would have been available to a defendant with money, doesn’t add up to what lawyers call a “legally cognizable claim.” Nor does the (closely related) fact that he was convicted solely on the basis of eyewitness testimony, even though social science research has demonstrated how unreliable such testimony often is.

If I were to attempt a sympathetic translation of Scalia’s dissent into nonlegal terms, it would go like this: “The defense in this case is claiming that there’s something unusual about Troy Davis’ situation, requiring extraordinary action on the part of the Supreme Court. But there’s nothing unusual about his situation. The American legal system routinely sentences people to long prison terms and even to death on the basis of dubious evidence, in trials featuring overburdened, underfunded, and marginally competent defense lawyers. Obviously under such conditions (a lot of) mistakes are going to be made. If such mistakes make verdicts unconstitutional, then the whole system is unconstitutional.”

And that, just as “obviously,” is an unacceptable conclusion.

The reflexive response to this sort of argument is the same one you often hear to people who defend using torture on terrorist suspects. That response is: This is America—we’re better than that.

To which the obvious reply is: No, we’re not.

Xtra Insight: Plus: Alan M. Dershowitz on Scalia’s Catholic betrayal.

Paul Campos is a professor of law at the University of Colorado at Boulder.