Illegal Stop by Police

Why does it matter if a police officer stops a person illegally? A police seizure may be a traffic stop or other Terry stop. But either way, a court must suppress all the evidence from an illegal stop. The prosecution can’t use it to charge or at trial.
The social harms of police seizures
When the government interferes with your liberty or property rights, the government must justify the violation. Under the law, a greater intrusion requires a greater fact-based justification.
American law uses different words to describe this justification. These include: reasonable, articulable suspicion of criminal activity, probable cause that a person has committed a crime, etc.
Leaving aside justification, what is the problem with police stops, or Fourth amendment seizures of people, anyway? After all, you’ve likely experienced a traffic stop. And apart from the ticket, you survived well enough.

Government seizures are not trivial: deaths can result
Unfortunately, some people do not survive a police stop without suffering injury or death, as news reports frequently remind us. So, sometimes police officers suffer injury or death. And other times it’s a suspected criminal. Even innocent, law-abiding citizens suffer injury or death due to a police contact – after what seemed a “routine” traffic stop.
Too many traffic stops for trivial reasons create other problems. And a big one is the disparate impact based on race of, for example, marijuana laws.
Harm reduction: Minimizing police contacts to those truly necessary can reduce these social harms caused by police contacts. Courts can reduce these harms by getting tougher on every illegal stop.
Legal Standard for a Fourth Amendment Seizure
Does is matter if the car or person is “already stopped” at the time of the Fourth Amendment seizure? No, it does not. Because you are not “free to leave.” So, fleeing police is also a crime.
Whether police had a lawful reason to detain a person and require information or compliance, is the real issue. A Fourth Amendment seizure happens when police assert government power to seize or detain a person.
The U.S. Supreme Court’s Terry vs Ohio
The Fourth Amendment of the Untied States Constitution affirms every individual’s right to be free from unreasonable searches. Police need a search warrant signed by a judge unless a court recognized exception to the warrant requirement applies.

A Terry stop allows the police to briefly detain someone if police have reasonable, articulable suspicion of criminal activity. Anything less is an illegal stop.
The U.S. Supreme Court’s case, Terry v. Ohio, 392 U.S. 1 (1968), held that police may briefly detain a person whom they reasonably suspect is involved in criminal activity.
Terry also held that police may sometimes conduct a limited search of the detainee’s clothes for weapons. But, for a Terry stop and frisk; police must have reasonable, articulable suspicion that the person is “armed and dangerous.”
To justify a stop, police must be able to articulate specific facts. And they must lead a reasonable police officer to believe that the person is engaging in criminal activity. Past conduct alone is not enough.

Traffic stops of motor vehicles
In addition to the “reasonable, articulable suspicion of criminal activity” standard for a brief detention; a traffic stop is also justified by an observed traffic or vehicle law violation.
Though most speeding violations are not a crime, a police officer can lawfully pull a driver over for speeding. Similarly, an equipment violation observed by a police officer can justify a traffic stop.
An illegal stop lacks both an observed violation and “reasonable, articulable suspicion of criminal activity.”
Two types of traffic stops
When it comes to Fourth Amendment seizures of people in motor vehicles, we have two categories of police justification claims:
- Observed traffic or equipment law violations, though not crimes.
- Facts observed amounting to “Reasonable, Articulable Suspicion of criminal activity” (or “RAS”).
Standards of proof; traffic or equipment violations
In a speeding trial to a judge, the prosecutor has the burden of admitting evidence into the trial court record. And the prosecutor attempts to persuade the judge of guilt beyond any (reasonable) doubt.
But, compare that to a pre-trial evidentiary hearing before a judge. The defense challenges whether a traffic stop was legal, which led to evidence of a crime (say, DWI). And assume the only justification for the stop was speeding.
While the prosecutor still must prove that the traffic stop was lawful; she need only prove that the police officer had an objective basis for believing that the driver was speeding.
The prosecution could lose the speeding ticket trial, after winning the stop challenge hearing. More evidence is necessary to convict than to justify a Fourth Amendment seizure.

Standards of proof – Reasonable, Articulable Suspicion of criminal activity
The legal standard for a Fourth Amendment seizure is lower than, for example, for Probable Cause to charge a crime.
The Reasonable and Articulable Suspicion of criminal activity (or, “RAS”) standard requires:
- objective reasons
- in the present tense
before a police officer can briefly detain a person. Or an observed petty misdemeanor or administrative violation ( though “not a crime”) can justify an initial Fourth Amendment seizure. Information police get after, cannot justify the stop.
If a judge does not believe there was an objective basis for the stop, she will suppress the resulting evidence.
The prosecutor won’t be able to use evidence from an illegal stop to support a criminal charge or at trial.
Your Criminal Defense Attorney
A good defense lawyer will consider whether a defense challenge to a Fourth Amendment seizure could be successful. Because most police investigations begin with a Terry stop, a successful challenge can mean a complete win for the defense.
The Fourth Amendment analysis does not end there, however. We also take a look at the level of intrusiveness and length of the detention and whether it was justified; as well as whether any subsequent search was illegal. Even if the initial reason for the stop was justified, police expansion of the stop may be illegal.

Minneapolis Criminal Attorney Thomas Gallagher‘s three decades experience challenging illegal stop cases can pay off for you.
Question? Call Criminal Attorney Thomas Gallagher: 612 333-1500
Washington Post video story with Attorney Thomas Gallagher
How ‘trivial things’ have become pretext for traffic stops
Link to video story^
“Minneapolis criminal defense attorney Thomas Gallagher explained on April 12 how police officers can use traffic stops to enforce laws that make ‘trivial things’ illegal.”