The Traffic Stop
Millions of Americans are pulled over by police each year for ordinary traffic violations. But a traffic stop in the United States often does more than enforce traffic laws: it creates an opportunity for the government to investigate a person who, moments earlier, may not have been suspected of any crime at all. A speeding ticket can become an OVI (Operating a Vehicle Impaired) investigation. A lane violation can lead to questions about drugs. A broken taillight can result in a search, a warrant arrest, or criminal charges entirely unrelated to the reason the officer initiated the encounter. We accept this as an ordinary feature of American policing. I am increasingly convinced that we should not.
I have traveled enough outside the United States to notice something that, once noticed, is difficult to ignore. In many places, particularly parts of Europe and Asia, you can drive considerable distances without seeing police officers positioned along the roadway waiting for a motorist to commit a traffic violation. Speed enforcement is often accomplished, at least in part, through cameras and other automated systems. A driver who speeds may receive a ticket, but the speeding violation does not necessarily create a face-to-face encounter with an armed government official who can begin investigating everything else about the driver.
The distinction matters.
In the United States, the traffic stop occupies a peculiar place in our criminal justice system. It begins with something mundane: speeding, a marked-lanes violation, an equipment issue, a registration problem. But once the emergency lights come on, an investigation that began with driving can quickly become an investigation of the person. Where are you coming from? Where are you going? Have you had anything to drink? Is there anything illegal in the vehicle? Can I search your car?
The Bureau of Justice Statistics estimates that approximately 12.4 million Americans age 16 or older were pulled over while driving in 2022. That makes the traffic stop one of the most common points of direct contact between citizens and law enforcement. For most motorists, nothing particularly consequential happens. They receive a warning or citation and continue on their way.
But as a criminal-defense attorney, I routinely encounter what happens when the traffic stop becomes something more. This is particularly apparent in OVI cases, where an investigation that ultimately focuses on alcohol or drugs may have begun with nothing more than an alleged speeding or lane violation.
A Minor Violation Can Open a Very Large Door
The constitutional law surrounding traffic stops creates an important practical reality. The United States Supreme Court held in Whren v. United States that when police have an objective legal basis for a traffic stop, an officer’s subjective motivation generally does not invalidate the stop under the Fourth Amendment. In other words, an observed traffic violation can provide the lawful basis for a stop even when the officer is interested in investigating something else.
There are constitutional limits. Most importantly, Rodriguez v. United States prohibits police from prolonging a traffic stop beyond the time reasonably required for its traffic-related mission merely to investigate unrelated criminal activity without the necessary independent reasonable suspicion. Those protections are significant, but constitutional rights written in judicial opinions and constitutional rights experienced on the side of a roadway at 11:30 at night are not always the same thing.
A motorist ordinarily does not know the precise boundaries of an officer’s authority. The motorist may not know when answering a question is optional, when consent may be refused, when a detention has been unlawfully prolonged, or even exactly why the officer stopped the vehicle. It is one reason I created an Ohio OVI Pocket Guide that people can save to their phones before they ever find themselves in that situation. Knowing your rights after an encounter has ended is very different from knowing what to do while standing on the side of the road with a police officer asking questions.
The officer, meanwhile, controls the encounter and creates much of the contemporaneous record of what occurred. That imbalance has consequences.
The Evidence Problem
When the legality of a police encounter is challenged in a criminal case, a suppression hearing can become the principal mechanism for asking a court to exclude evidence obtained through an unconstitutional search or seizure. But suppression litigation exposes a fundamental evidentiary problem.
The government has an institutional apparatus for collecting evidence. Police officers are present when the encounter occurs. They write reports. They operate cruisers equipped with cameras. They wear body cameras. They interview witnesses. They collect physical evidence. They access databases. And when charges are filed, prosecutors inherit the evidence produced by that system.
The ordinary citizen has no comparable apparatus. There is no defense investigator riding in the passenger seat when the emergency lights appear. There is no defense body camera recording what happened from the motorist’s perspective. There is no lawyer sitting beside the driver saying, You don’t have to consent to that.
Instead, the defendant frequently arrives at a lawyer’s office days or weeks later with an imperfect memory of a stressful encounter and little understanding of which facts are legally important. The defense attorney then reconstructs the event largely from evidence generated by the same governmental actors whose conduct may be challenged.
Body cameras have substantially changed this dynamic because they can provide evidence independent of an officer’s later recollection. But cameras have limitations. They do not necessarily show what an officer claims to have observed before activating the camera. They may not capture the officer’s precise vantage point. They cannot record an unspoken reason for extending an investigation. And sometimes the constitutional question turns on seconds, positioning, visibility, or events outside the camera’s field of view.
That can leave a troubling gap between possessing a constitutional right and possessing enough evidence to prove that the right was violated.
Perhaps We Should Ask a Different Question
The usual debate begins after the traffic stop: Did the officer have reasonable suspicion? Was consent voluntary? Was the detention prolonged? Was the search lawful? Those are necessary questions. As a defense attorney, I litigate them.
But there is another question worth asking:
Why do we create so many discretionary police-citizen encounters in the first place?
This is where my experiences abroad have caused me to think differently about American traffic enforcement. Automated enforcement raises legitimate concerns of its own. Accuracy, privacy, due process, governmental surveillance, and the fairness of fines all deserve serious scrutiny. It would be naïve to suggest that replacing officers with cameras automatically produces a fairer system.
But automated enforcement does reveal that two governmental functions we often treat as inseparable are actually distinct: enforcing traffic laws and investigating the people who violate them.
We can enforce traffic laws without necessarily creating an opportunity to investigate the driver.
A camera designed to enforce a speed limit does not smell marijuana. It does not ask where the driver is going. It does not notice nervousness. It does not request consent to search the trunk. It does not turn a speeding ticket into an OVI investigation, a drug investigation, a warrant arrest, or an inquiry into some unrelated suspected offense. That can be viewed as a limitation. It can also be viewed as a safeguard.
This Is Not an Argument Against Policing
Police officers perform functions that automated systems plainly cannot. Dangerous drivers must sometimes be stopped immediately. Suspected impaired drivers cannot simply be mailed citations. Police respond to violence, emergencies, crashes, and people who need immediate assistance. Nor does every traffic stop become a fishing expedition. Most do not.
The more important question is structural rather than personal. If we design a system in which millions of relatively minor traffic violations generate discretionary investigative encounters between citizens and police, we should expect some of those encounters to expand into investigations unrelated to the conduct that originally justified the stop.
And that leads to a question I believe deserves far more attention:
How much criminal conduct does our system discover not because police were investigating that conduct, but because we have chosen to subject millions of motorists to discretionary roadside encounters while enforcing traffic laws?
Once a person enters the criminal justice system, the consequences can extend far beyond the offense appearing on the citation or complaint: attorney fees, court appearances, missed work, license consequences, probation requirements, and the collateral consequences associated with a criminal record. Those downstream consequences deserve their own discussion. My concern here begins earlier—at the moment the emergency lights come on.
Constitutional Rights Are Most Important Before Anyone Knows They Will Need Them
Americans rightly take pride in the protections contained in the Fourth Amendment. We require legal justification for seizures. We regulate searches. We permit courts to suppress evidence obtained through certain constitutional violations. But a constitutional system should not evaluate liberty exclusively by asking whether a lawyer can successfully prove a violation afterward. It should also ask how frequently the government creates situations in which violations can occur.
That is why traffic enforcement deserves more attention in discussions about criminal justice reform. Perhaps some violations require an officer on the roadside. Perhaps others can be handled through technology or civil enforcement mechanisms. Perhaps certain minor violations should not serve as routine gateways into broader criminal investigation. And perhaps automated enforcement presents problems significant enough that other alternatives are preferable.
Those questions require evidence and serious debate. But the starting point should be recognition of something criminal-defense lawyers see repeatedly:
A traffic stop is not always just a traffic stop.
It is one of the principal places where an ordinary person—someone driving to work, taking a child home, visiting a friend, or returning from dinner—can suddenly move from everyday life into the machinery of the criminal justice system.
We rightly expect police to investigate crime. But there is a meaningful difference between investigating someone because there is reason to suspect a crime and creating millions of encounters in which an investigation might develop. Traffic enforcement has quietly blurred that distinction.
Enforce the traffic laws. But whenever reasonably possible, do it without turning the driver into the investigation.
Brandon Harmony is an Ohio attorney and the founding partner of Harmony Law. His practice includes criminal defense and OVI defense, where he represents individuals navigating police investigations, traffic stops, and the criminal justice system.