Parsing the Three Opinions in Kansas v. Glover

Initially, the 8-1 vote in Kansas v. Glover, noted earlier today, was somewhat surprising. Reading through the three opinions in the case, we see some important differences that go beyond the result on the sparse facts of this case.

The Decision

Procedurally, the case was unusual in that the defendant’s motion to suppress evidence was decided on stipulated facts without a hearing. The officer ran the license plate, found that the registered owner had a revoked (not suspended) license, made no effort to identify the driver, and made the stop. That’s it.

It is well established that a brief stop requires “reasonable suspicion” that criminal activity is afoot, a considerably lower standard than the “probable cause” required for an arrest. Do the stipulated facts amount to reasonable suspicion? If we see Chuck’s truck on the road and know that Chuck’s license is revoked, are we reasonable to suspect that Chuck is driving it and thus violating the law.

Yes, on those bare facts, but Justice Thomas’s opinion for the Court notes some variations on the theme that might produce different answers, and Justice Kagan adds some more in her concurrence, joined by Justice Ginsburg. (Note that both join the majority opinion as well. Justice Kagan’s opinion is a concurrence, not a “concurrence in the judgment” without joining the majority opinion, as judges sometimes do.)

Both reasonable suspicion and the higher standard of probable cause are probability judgments. The required probability goes up as the consequences to the person affected goes up. A brief stop requires only suspicion, a bar that ” ‘falls considerably short’ of 51% accuracy,” the Court says, quoting a 2002 case. A greater probability is required to arrest a person and put him on trial, and conviction requires the steep “proof beyond a reasonable doubt.”

Disputed Statistics

So Chuck may very well have allowed a properly licensed family member or friend to drive his truck, and that person would be inconvenienced by the stop. Even so, the probability that Chuck himself is behind the wheel is large enough that we can reasonably suspect it is him, and that is enough. The Court noted research that confirms common experience. A full 75% of drivers with suspended or revoked licenses drive anyway. The Court also noted a weighty consideration in this matter, even if not affecting the probabilities, that 19% of fatal accidents in a four-year period “involved drivers with invalid licenses.” That is a very big body count, and reducing it justifies a minor inconvenience to people driving the vehicles of the license-revoked people.

Justice Sotomayor, in dissent, asserts, “Neither report even offers a useful denominator.” The 75% statistic conflates the suspended drivers with the revoked drivers. That is a valid criticism, whether or not correctly denominated a denominator problem. The percentage for revoked-license drivers could probably be found in the studies that the report cites. If it is not in the published reports of the studies, the answer is surely in the data, if that is still available. I suspect that revoked-license drivers are at least as likely to violate the law by driving as suspended-license drivers, if not more so, but it is worth checking.

Justice Sotomayor goes on to say, “The figures say nothing about how the behavior of revoked drivers measures up relative to their licensed counterparts—whether one group is more likely to be involved in accidents, or whether the incidences are comparable—which would inform a trooper’s inferences about driver identity.” There seem to be two criticisms commingled in one sentence here.

To the extent she is saying that the 19% figure says nothing about whether revoked-license drivers are more likely to be in accidents, that is an overstatement. The figure would be more useful if coupled with the percentage of drivers whose licenses have been revoked, but unless that percentage is 19% or greater, which is extremely unlikely, the 19% by itself is enough to show a disproportionate number of revoked-license drivers are involved in fatal accidents. Again, though, this is worth following up to get more precise figures.

To the extent Justice Sotomayor is saying this figure does not inform identity, that is true. This goes more to general reasonableness than to the probability of identity. Reasonableness, after all, is “ultimate touchstone of the Fourth Amendment,” as the Court notes once again in the present case. Failure to get known-unsafe drivers off the road will kill a lot of innocent people, and that matters, whether it fits in the formula or not.

See also the “denominator” note at the end of the post.

Probability and Common Sense

The stipulated-facts hearing provides us no insight into the officer’s actual thought process. Is that a problem? Justice Sotomayor thinks it is. From Chief Justice Warren’s original “stop and frisk” opinion way back in 1968, Terry v. Ohio, the Court has frequently spoken in terms of suspicion as viewed by a police officer in light of his training and experience. Testimony along those lines is standard procedure in stop cases. Do those statements mean that only specialized training and experience may inform the officer’s judgment, to the exclusion of common sense and common experience shared with the general population?

The majority doesn’t buy it. Special training and experience are important, but ordinary experience and knowledge of human behavior count also. A person who takes off running at the sight of the police might have an innocent reason for doing so, but there is reason to suspect a guilty one. Buying a business-fare airplane ticket in cash is unusual behavior these days. It would not be reasonable suspicion by itself, but it is a pebble on suspicion’s side of the scale that the buyer just might be a drug runner. These are matters of common knowledge, and they contribute to the overall picture. Justice Kagan notes in her concurrence:

When you see a car coming down the street, your common sense tells you that the registered owner may well be behind the wheel…. Not always, of course. Families share cars; friends borrow them. Still, a person often buys a vehicle to drive it himself. So your suspicion that the owner is driving would be perfectly reasonable.

Justice Sotomayor warns ominously that “[t]he majority today has paved the road to finding reasonable suspicion based on nothing more than a demographic profile.” It might if we did not have barriers against that. The majority notes in footnote 1 that precedent precludes forming the requisite suspicion from demographic factors.

All the Circumstances

The Supreme Court long ago gave up on rigid formulas in Fourth Amendment cases and held that probable cause and reasonable suspicion must be judged on the facts of each case. See Illinois v. Gates (1983). The majority notes that other cases with different facts might produce a different result.

For example, if an officer knows that the registered owner of the vehicle is in his mid-sixties but observes that the driver is in her mid-twenties, then the totality of the circumstances would not “raise a suspicion that the particular individual being stopped is engaged in wrongdoing.”

Note the gender shift in the possessive pronouns. Demographic factors are legitimate in determining whether an observed person fits the general description of a known person.

In this case, the officer had enough information to make the stop before he saw the driver sufficiently to obtain that kind of information, but that will not always be the case. Justice Kagan devotes her concurring opinion to spelling out how other cases may be different.

Justice Kagan stresses that Glover’s license was revoked, not suspended, and that Kansas only revokes licenses for weighty reasons involving serious violations. A revocation thus points to a disregard for law in a way that suspension often does not. A license may be suspended for reasons other than driving, which may include financial inability to pay certain obligations.

What if the car had two registered owners, one with a valid license and one with a revoked license? If the officer is unable to rule out the validly licensed driver by observation, does reasonable suspicion still exist? That is a much tougher question.

The Bottom Line

The Court has not given a green light to police officers to stop every car registered to a person with a suspended or revoked license. Although the stop was upheld in this case, officers would be well advised to get a look at the driver to see if he matches the sex and approximate age on the revoked license, at least, before making the stop.

Post Script: The Fallacy of the Irrelevant Denominator

As an aside, I am glad to see that Justice Sotomayor is aware of the Fallacy of the Irrelevant Denominator. I hope to see this awareness in operation the next time someone makes the argument that the number of people in group A in prison for a given crime is “disproportionate.”

Let GP(A) and GP(O) be the number of people in the general population in group A and overall, respectively, P(A) and P(O) be the numbers in prison for the given crime from group A and overall, respectively, and C(A) and C(O) be the numbers who commit the crime from group A and overall, respectively. The fact that P(A)/GP(A) > P(O)/GP(O) is irrelevant. The first cut in a disproportion argument should be that P(A)/C(A) > P(O)/C(O). Prison is for people who commit serious crimes, not the general population, so the general population is an irrelevant denominator. If the advocates are not citing the latter inequality, it is probably because it is not true.