DWI Traffic Stops in Minnesota: When Is a Stop Legal?

The Standard: Reasonable, Articulable Suspicion

A traffic stop is a "seizure" under the Fourth Amendment and the Minnesota Constitution. To make one, an officer needs reasonable, articulable suspicion — specific, objective facts suggesting a traffic violation or other criminal activity. A hunch isn't enough. If the stop wasn't justified, evidence obtained afterward can be suppressed. (For the general law of traffic stops and what police can do during one, see our traffic stops and vehicle searches page.)

What Justifies a DWI Stop

In practice, most DWI stops rest on one of two things:

• An observed traffic violation — speeding, an illegal turn, a burned-out light, failure to signal, equipment problems. Even a minor violation can justify a stop; and
• Driving conduct suggesting impairment — for example, weaving, erratic speed, or near-collisions, especially combined with time of night or location near bars.

Pretext doesn't automatically invalidate a stop. If you actually committed a traffic violation, the stop is generally valid even if the officer's real goal was to investigate a possible DWI. That's why the key question is usually whether a real, objective basis for the stop existed — which is worth examining closely against dashcam and bodycam footage.

The Weaving Question

One of the most litigated issues in Minnesota DWI stops is weaving:

• Weaving within your own lane — a single drift or touching a lane line without crossing it — is generally not a traffic violation and often is not enough by itself to justify a stop, particularly where road, weather, or conditions offer an innocent explanation; but
• Continuous or unusual weaving, or actually crossing out of the lane, frequently will support a lawful stop.

Because so many DWI stops rest on claimed weaving, this is a fact-sensitive issue where the video and the specifics genuinely matter.

A Key Minnesota Rule: Mistake of Law vs. Mistake of Fact

This is one of the most important — and least known — protections in Minnesota stop law, and it's an area where Minnesota is more protective than federal law:

• Mistake of law — not allowed. If an officer pulls you over because they misunderstood what the law actually prohibits — believing conduct was illegal when it wasn't — that stop is invalid in Minnesota, even if the officer acted in good faith. An officer's mistaken interpretation of a statute cannot supply the reasonable suspicion needed for a stop. (This differs from the federal rule, which allows some objectively reasonable mistakes of law.)
• Mistake of fact — can be reasonable. By contrast, a stop based on a reasonable mistake about the facts can still be valid. For example, if an officer reasonably believes the registered owner's license is suspended and stops the car, the stop can hold up even if it turns out someone else was driving.

No Sobriety Checkpoints in Minnesota

Many people assume DWI roadblocks and sobriety checkpoints are legal because they're common in other states. In Minnesota, they're not. Minnesota's courts have held that DWI checkpoints violate the Minnesota Constitution — so a stop in Minnesota generally has to be based on individualized suspicion, not a suspicionless checkpoint.

What Is Not Enough on Its Own

Some facts, standing alone, don't justify a stop:

• Mere presence in a high-crime area, or being a stranger to an area;
• A single in-lane drift with an innocent explanation;
• Innocent, ordinary driving conduct without more.

That said, the test isn't whether the conduct was ultimately innocent — it's the degree of suspicion the conduct reasonably created at the time. Conduct that turns out to be innocent can still have justified a stop if it was genuinely suspicious in the moment.

Tips and Informants

Stops based on tips (for example, a 911 call reporting a possible drunk driver) turn on the reliability of the information — an identified citizen informant is generally treated as more reliable than a bare anonymous tip, which usually needs some corroboration or detail. (Our police stops and detention page covers informant-based stops in more detail.)

Why the Stop Is the First Thing to Examine

Because everything in a DWI case flows from the stop, challenging the stop's legality is often the highest-value move in the defense. If the stop was unlawful — no real violation, a mistake of law, an unjustified weaving claim, an unreliable tip — the remedy can be suppression of the evidence that followed, which can undermine or end the case. A careful review of the officer's stated basis against the video and the facts is where that analysis starts.

Key Terms

• Reasonable articulable suspicion: The objective, fact-based standard required to make a stop.
• Pretextual stop: A stop for a minor violation used to investigate something else — valid if a real violation occurred.
• Mistake of law: Stopping someone for conduct that isn't actually illegal — invalid in Minnesota.
• Mistake of fact: A reasonable factual error — can still justify a stop.
• Suppression: Excluding evidence obtained from an unlawful stop.