Last month, the U.S. Supreme Court heard argument in Rodriguez v. United States. Rodriguez presents the question whether, after completing the steps necessary to a routine traffic stop, a police officer may briefly delay the release of a driver to permit a dog sniff for narcotics. The petitioner claims that such conduct, however brief, constitutes an unjustified and thus unreasonable seizure of the person, in violation of the Fourth Amendment. In this column, I will consider some of the interesting lines of argument in this case that captured the Justices’ attention during oral argument.

Dog Sniffs and Traffic Stops

In a number of cases, including Illinois v. Caballes, the U.S. Supreme Court has said that a dog sniff for drugs is not a Fourth Amendment “search” triggering the requirement that it be “reasonable.” In the language of the 1967 case of Katz v. United States, having a dog sniff a suspect’s property for contraband invades no “reasonable expectation of privacy.” Because the only information or matter exposed by the dog to his or her police officer handler in the course of a dog sniff is that the target either does or does not possess contraband, a dog sniff leaves intact all innocent and legitimate privacy.

Police rummaging through a car trunk or a suitcase, by contrast, threatens innocent privacy by exposing private items in which innocent people do legitimately maintain a “reasonable expectation of privacy,” entitled to protection from police investigation. To say that a dog sniff is not a search means that, unlike opening a suitcase or a car trunk, police may conduct a dog sniff for narcotics without acquiring a warrant or probable cause or even an iota of reason to suspect that the target of the investigation is in possession of narcotics.

The Rodriguez case does not challenge the Court’s existing precedents regarding dog sniffs. Instead, it challenges the legitimacy of extending the length of a routine traffic stop in order to allow for a dog sniff as an additional investigative technique, beyond the ordinary process of addressing a traffic violation. In Caballes, the case in which the Supreme Court squarely held that dog sniffs are not Fourth Amendment searches, the Court upheld the dog sniff there (which was itself conducted during a routine traffic violation stop), because the sniff occurred while the traffic stop was in progress and did not extend the duration of the stop. Since the sniff did not constitute a search and did not require a seizure (beyond the duration of the seizure already lawfully in progress), the Court held that the police conduct in Caballes did not implicate the respondent’s Fourth Amendment rights at all.

In Rodriguez, the district court adopted the recommendation of the magistrate judge in the case. This adoption likely included the magistrate’s finding that the officer who conducted the dog sniff of Dennys Rodriguez lacked reasonable suspicion to justify further detention at that point, though the magistrate (and the district court) nonetheless approved the detention for a dog sniff as “de minimis” under Eighth Circuit precedent. The U.S. Court of Appeals for the Eighth Circuit then ruled that even if the officer lacked reasonable suspicion—a question that the Court of Appeals felt no need to reach—the brief extension of the traffic stop that was necessary to carry out a dog sniff was sufficiently minor not to violate Rodriguez’s Fourth Amendment rights. It was, again under Eighth Circuit precedents, “de minimis,” denoting a trivial and insubstantial infraction, unworthy of legal remedy.

Two Questions That Attracted the Court’s Attention

One question that divided some of the Justices at oral argument was whether the sequence of an officer’s investigative measures ought to matter to the Fourth Amendment. Rodriguez’s attorney argued that what made the officer’s conduct in this case a clear violation of the Fourth Amendment was the fact that the traffic stop was over, the police officer had issued a written warning, and the detention for the dog sniff thus took place during a time at which there was (assumed to be) no basis for holding the driver. By implication, then, had the dog sniff occurred before the business of the traffic stop was complete—before the officer had written up the ticket—then the case for arguing a Fourth Amendment violation might not have been as clear-cut.

Both the government attorney and several Justices commented, in response to such argumentation, on how arbitrary this sequencing line would be. As Justice Alito put it, “[i]f we hold that it’s okay to have a dog sniff so long as it’s before the ticket is issued, then every police officer other than those who are uninformed or incompetent will delay the handing over of the ticket until the dog sniff is completed. So what has that—what does that accomplish?”

If the stop lasts eleven minutes instead of twelve, because of the dog sniff, then the additional minute of detention is presumably no less intrusive to the driver if it comes last than if it comes in between the ten minutes of legitimate, traffic-inquiry-related detention. The government attorney argued further that either way, the additional intrusion, when minor and when leaving the duration of the entire stop within the time that a reasonable traffic stop would take without a dog sniff, as occurred in this case, should be considered reasonable under the Fourth Amendment.

What’s Part of the Traffic Stop Mission?

In addition to the sequencing question above, another issue that interested the Justices is what sorts of steps really are a legitimate part of the police officer’s “traffic stop” mission? That is, what questions and/or conduct by police justifiably take time as an incident of conducting a traffic stop and which questions and conduct must occur—if at all—only while other, traffic-stop-relevant activities are taking place? Several Justices noted that the police routinely do a license check on the driver subject to a traffic stop and thereby find out, among other things, whether the driver has a record of crime and/or other violations.

Yet a driver’s swerving out of his lane or driving with a broken taillight seems to have nothing to do with prior crimes or violations. Why, then, does the police officer get to take as much time as necessary to pursue this information as part of a routine traffic stop, whereas the dog sniff must either occur simultaneously with these other steps or, according to the government attorney, must occur within a brief enough time that the entirety of the traffic stop takes no longer than is generally reasonable for a traffic stop absent a dog sniff? What is the difference between non-traffic-offense-related questions and records-checking, on the one hand, and a dog sniff, on the other?

The question is particularly pertinent in this case, because the Supreme Court has already said, in Arizona v. Johnson, that “[a]n officer’s inquiries into matters unrelated to the justification for the traffic stop, this Court has made plain, do not convert the encounter into something other than a lawful seizure, so long as those inquiries do not measurably extend the duration of the stop.” Is this flexible approach applicable only to questions or does it apply to dog-sniff-related detention as well?

Chief Justice Roberts offered a quick answer to the “what’s the difference?” question. He said that once a police officer pulls over a suspect and asks for license and registration, the officer is now potentially quite vulnerable to violence from a suspect who may have a criminal record. Accordingly, the officer is entitled to find out with what sort of person he is dealing so that he can call for backup if necessary.

However long it takes to write a ticket and return to the driver to give back the license and registration, this rationale entitles the officer to know what sort of person awaits his return (perhaps a fugitive wanted for murder). Finding out whether there are drugs in the car, on the other hand, seems to represent a complete change of subject.

If Chief Justice Roberts is correct here, and I think he is, then I do not expect we will see the Court either questioning the police practice of checking a stopped driver’s prior record or taking the view that a dog sniff (even if it takes a long time) constitutes a normal and routine incident of a traffic stop. Whether it is qualitatively different from asking about other “matters unrelated to the justification for the traffic stop,” as in Johnson, remains to be seen.

What made the oral argument in this case so interesting was that the Justices took the opportunity to question long-accepted features of the routine traffic stop to see whether their logic holds up to critical scrutiny. It also delved into the importance (or unimportance) of sequence in a sophisticated fashion. However the Court ultimately decides the limited question presented in Rodriguez, I am pleased to see it grappling with long-held assumptions in its efforts to resolve a relatively narrow question about the proper duration of a traffic stop.