This is Part Two in a two-part series of columns. Part One in the series appeared here on Justia’s Verdict on Wednesday, October 16. –Ed.

In Part One of this series, I began examining Navarette v. California, a case in which the U.S. Supreme Court will decide whether anonymous tips are sufficient to create reasonable suspicion to support a stop. I reviewed the relationship between probable cause and reasonable suspicion as well as the role of known informants and anonymous informants in helping police meet each of these standards, in turn, to shed light on what is normally required to justify an arrest or stop. Here, I focus on the Navarette case itself.

Facts of Navarette v. California

In Navarette v. California, a police dispatcher received a call from an anonymous informant. The informant claimed to have been run off the road by a reckless driver. The informant supplied the make, the model, and the plate number of the car in question, as well as the approximate timing of the encounter with the allegedly reckless driver and the direction in which the driver was headed. The dispatcher passed along some portion of this information to another dispatcher, who broadcast it over the police radio.

Several police officers, after hearing the broadcast, drove to where they expected to find the accused reckless driver, based on the informant’s tip. They did, in fact, spot the driver in question and followed him for a few minutes, after which they pulled over the driver and his passenger (his brother and future co-defendant). As often tends to happen in the cases that make it to court, the police detected the smell of marijuana when they approached the vehicle and subsequently searched the car and found a large quantity of marijuana. The D.A. charged the men with transporting marijuana.

Prior to pleading guilty, the defendants moved to exclude from the evidence in the case the marijuana found in the car, arguing that it was the fruit of a Fourth Amendment violation—a stop without reasonable suspicion. The motion to suppress was denied, and the two men subsequently pleaded guilty to transportation of marijuana. The defendants continue to claim that police lacked reasonable suspicion to justify a stop of the vehicle, and that the evidence they found during the subsequent vehicle search was all “the fruit of the poisonous tree” and thus should have been suppressed. Absent that evidence, the two defendants would not have pleaded guilty.

Watching the Car Before Pulling It Over

The case contains an interesting twist. The police did not simply pull over the driver when they first spotted him. They instead followed him for a few minutes, presumably to see whether they might observe reckless driving on their own, thus obviating the need to rely entirely on the anonymous informant’s tip to establish reasonable suspicion. The driver did not oblige, however, and apparently drove carefully during the time in which the police were following him.

Had the police immediately pulled over the driver, it might have been easier to defend what the officers did. The accusation, after all, was that the driver had run the anonymous caller off the road, a plainly reckless thing to do while driving. And from this accusation, if believed, police might have reasonably concluded that the driver could be expected to continue driving in a reckless fashion if not stopped. Once police spied the vehicle that had allegedly been involved in running the informant off the road, it might therefore have appeared urgent to the police to stop the vehicle immediately, despite the bare bones nature of the anonymous informant’s tip.

Bare Bones Anonymous Tips

The U.S. Supreme Court decided Illinois v. Gates the leading anonymous tipster case (in which the Court also loosened the probable cause standard) thirty years ago. In the 2000 case of Florida v. J.L., the Court once again had occasion to opine on the question of relying on anonymous informants’ accusations, absent guilty-fact corroboration. In that case, the Court held that to have reasonable suspicion for a stop, police needed more than an anonymous tip that precisely and accurately identified a particular suspect but otherwise provided unsubstantiated accusations of wrongdoing.

In J.L., the anonymous informant called the police and reported that “a young black male standing at a particular bus stop and wearing a plaid shirt was carrying a gun.” This, the Court held, was inadequate to establish reasonable suspicion, despite the fact that police did, in fact, find an African American man in a plaid shirt at the designated bus stop. Most relevantly for purposes of Navarette, the Court in J.L. said that a tip that accurately provides a suspect’s location and appearance “does not show that the tipster has knowledge of concealed criminal activity. The reasonable suspicion here at issue requires that a tip be reliable in its assertion of illegality, not just in its tendency to identify a determinate person.” (emphasis added).

In dictum, however, the Court noted that there could be cases in which a bare accusation of this sort might suffice. It gave the example of a report of someone carrying a bomb. If police received a call identifying a particular suspect and saying that he or she was holding a bomb, the police could perhaps lawfully stop the suspect on the basis of that call, despite the caller’s anonymity and the lack of what would ordinarily qualify as sufficient detail and of testable and accurate predictions.

On the basis of that line in the Court’s opinion, a number of courts have approved stops of drivers against whom anonymous accusations of reckless or drunk driving had been made. A reckless driver, in this view, is like a bomb in that he, she, or it poses an imminent threat to the population. Other courts, however, have relied on the main holding of J.L. to conclude that such anonymous accusations would fall short of supplying reasonable suspicion to the police, absent corroboration of some guilty facts.

More or Less Like a Bomb Than the Gun in J.L.?

One could distinguish the facts of J.L. (man with firearm) from the facts of Navarette (man driving recklessly). A report of a driver running an informant off the road is arguably more concrete and threatening than a report of a suspect being in possession of a firearm. One could be in possession of a firearm, even an illegal one, without posing an immediate threat to anyone. By contrast, a driver who just ran another driver off the road appears to be posing an immediate danger to other drivers and to pedestrians, much as someone with an illegal firearm accused of just now randomly shooting into a crowd would.

On the other hand, in Navarette, the police decision to follow the reported vehicle for a few minutes potentially does two things to undermine the case for reasonable suspicion. First, it may betray the officers’ own worry that they so far lacked a sufficient basis for stopping the vehicle. One could, however, respond that the officers had reasonable suspicion but were hoping to acquire more evidence of reckless driving before invading the suspect’s liberty, to their credit.

A second problem, however, is that if police are facing what they regard as an emergency—one that justifies a stop that might otherwise be unfounded, in the way that a bomb-holding suspect might—then it seems odd for the police to allow the driver to continue driving for several minutes before actually pulling him over. If the police suspected a bomb were about to be detonated —to cite the example that the Supreme Court itself offered— police would likely have acted immediately to end the threat.

If, as the Court has indicated, one generally needs more than an anonymous tip containing a precise identification to justify a stop, absent an emergency requiring preventive intervention, then the officers’ failure to stop the identified car immediately could be said to belie a claim of emergency, and counsels adherence to the more general rule.

Going Back to Reasonable Suspicion’s Roots

The mention of a “bomb exception” in J.L. may sound somewhat ad hoc to readers, but I think it actually has in it the promise of coherence. The bomb exception points us back to an original reason for allowing police to detain a suspect briefly without probable cause: the special law enforcement need to intervene in a preventive capacity before a crime has occurred. This was the implicit logic of Terry, explicated in greater detail in Justice Harlan’s concurring opinion in that case, and it explained a departure from the rule that police need probable cause to detain an individual: police function not only as investigators of completed offenses but as people who keep the streets safe, and deter and otherwise frustrate the commission of crime in the first place. It was, I would argue (and did argue, in an article titled The Qualitative Dimension of Fourth Amendment “Reasonableness”) a mistake to extend the authority to briefly detain people beyond the implicit “special law enforcement” interest in Terry (and made explicit in Justice Harlan’s concurrence there).

If we were to return to this original rationale, then we would ask, when police receive an anonymous accusation of reckless driving, directed at a precise target: Do we in fact have an emergency on our hands? If so—for example, if police reasonably believe on the basis of the tip that a drunk driver continues to endanger the safety of pedestrians and other drivers—then police should, by all means, pull over the specific driver identified by the informant. If, on the other hand, the goal is simply to apprehend someone who has already committed an offense—whether a drug crime, a violent crime, or a traffic-related crime (like running another driver off the road) —then police ought to have something more before proceeding. And whether that “more” means some corroboration of incriminating facts, or whether it simply means more evidence (amounting to probable cause, rather than just reasonable suspicion) may be less important than limiting any “preventing danger” detention on less than probable cause to circumstances in which police are truly acting to guard the public from an imminent threat.