H. Michael Steinberg has 42+ years of experience practicing Colorado criminal law. Mr. Steinberg strives to stay current with the ever changing aspects of criminal law issues and updates resulting in his extensive knowledge of successful criminal defense as well as appellate work. He is also an active member of the National Association of Criminal Defense Lawyers, the Colorado Criminal Defense Bar Association, the Colorado Trial Lawyer's Association, and the Colorado and Arapahoe Bar Associations.
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What Colorado’s New Breath-Test Rule Means for DUI and Vehicular Homicide Cases: Magnus’ Law

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What Colorado’s New Breath-Test Rule Means for DUI and Vehicular Homicide Cases: The Magnus Law

By H. Michael Steinberg, A Colorado Criminal Defense Lawyer – Practicing Colorado Criminal Law in the courts of Colorado for over 40 years.

Colorado's New Breath-Test Rule Means for DUI and Vehicular HomicideIntroduction – Why It Is Called Magnus’ Law

On July 29, 2023, 17-year-old Magnus White — a member of the USA Cycling National Team preparing to leave for the world championships in Scotland — was struck and killed by a vehicle while training on his bike along Highway 119 near Boulder. Investigators later found evidence that the driver of the car had been drinking and taking prescription medication in the hours before the crash.

But at the scene, none of the responding officers asked the driver to take a breath test or a field sobriety test. By the time investigators circled back, the moment to capture that evidence was gone.

The Defendant was ultimately convicted of reckless vehicular homicide and sentenced to four years in prison — but never charged with DUI, because the state had no test result to prove it

Magnus’s parents spent the next two years pushing lawmakers to close that gap. The result, signed by Governor Jared Polis in June 2026, is Senate Bill 26-132 — known as Magnus’ Law — which took effect at 12:01 a.m. on August 12, 2026.

For anyone facing a Colorado DUI, vehicular assault, or vehicular homicide investigation in Colorado, the new law changes how — and how quickly — the state gathers its most important piece of evidence: proof of intoxication at the scene.

What Magnus’ Law Requires

Magnus’ Law amends Colorado’s traffic code, C.R.S. § 42-4-1301, to add a new, narrow mandate.

When a crash results in a death or a suspected serious bodily injury, an officer must now offer the driver believed to be at fault the chance to voluntarily take a preliminary breath test — but only when three conditions are all met (SB26-132 bill text):

    1. The officer has reasonable suspicion that the person was the driver and was at fault in the collision;
    2. The driver is not seriously injured or in need of immediate medical attention; and
    3. The officer does not already have probable cause to demand an admissible chemical test under Colorado’s Expressed Consent Law.

Before asking, the officer must advise the driver — in plain language — that:

    1. The request is because they were involved in a serious collision;
    2. The test is voluntary; neither the result nor a refusal can be used against them in court;
    3. A positive result may still be used to request further, admissible testing or to make an arrest; and
    4. Refusing has no effect on their driver’s license.

The mandate has real limits.

An officer doesn’t have to offer the test if their first contact with the driver comes more than two hours after the crash, or if the driver left the scene before law enforcement realized someone had died or been seriously hurt.

And critically,

…the test itself remains exactly what it always was under Colorado law: voluntary, and inadmissible as direct proof of guilt.

How This Fits Colorado’s Existing DUI Framework

It’s easy to confuse Magnus’ Law with Colorado’s long-standing Expressed Consent Law, but they operate at different stages of a stop.

Before an arrest: Colorado has always allowed — but never required — an officer with reasonable suspicion of impairment to offer a preliminary breath test, and a driver under 21 suspected of any drinking can be offered one too (C.R.S. § 42-4-1301(6)(i)).

That pre-existing roadside test is still voluntary, and refusing it carries no direct penalty. Magnus’ Law simply carves out a specific, high-stakes scenario — a fatal or serious-injury crash where the officer doesn’t yet have probable cause — and turns that discretionary offer into a mandatory one.

After an arrest: Colorado’s Expressed Consent Law, C.R.S. § 42-4-1301.1, takes over: once an officer has probable cause to believe a driver is impaired, the driver is deemed to have already consented to a blood or breath chemical test, and refusing that test — unlike the preliminary roadside version — triggers automatic license consequences, including “persistent drunk driver” designation even for a first offense.

Magnus’ Law doesn’t touch that post-arrest framework at all. What it changes is the moment before probable cause exists — the exact gap that let the driver who killed Magnus White walk away from the scene without ever being tested.

Why This Matters for a DUI or Vehicular Homicide Defense

Because a preliminary breath test offered under Magnus’ Law can lead directly to an arrest and, eventually, to an admissible chemical test, the new mandate opens several fact-specific issues a defense attorney should scrutinize in any serious-crash case investigated after August 12, 2026.

The Advisement Script Is Now a Checklist — and a Target

The statute requires officers to deliver a specific set of warnings before requesting the test. If body-camera footage or an incident report shows an officer skipped the “voluntary” or “not admissible” advisement, or pressured a driver into believing the test was mandatory, that creates a genuine argument that any resulting consent — and anything that flowed from it — wasn’t truly voluntary.

The Two-Hour Window and “Left the Scene” Exceptions Cut Both Ways

Because the mandatory offer only applies within a defined window, timelines matter more than ever. When exactly did the officer make “lawful contact” with the driver? When did law enforcement first learn the collision involved a death or serious injury?

A Colorado criminal defense attorney reconstructing the minute-by-minute timeline from dispatch logs, body-camera timestamps, and witness statements can sometimes show the mandatory-offer window never actually applied — which matters if the state later argues the officer’s failure to test was itself suspicious.

A Refusal Still Cannot Be Used As Evidence of Guilt At Trial

The law is explicit that neither a positive preliminary result nor a refusal is admissible in court. If a prosecutor’s narrative leans on “the defendant refused the test” as circumstantial proof of intoxication, that’s a direct challenge point — the statute itself forecloses that inference.

A Positive Preliminary Result Is Just the Beginning, Not the End

A preliminary breath test is inherently less reliable than an admissible evidentiary breath or blood test — it’s a screening tool, not a conclusive measurement. Where a positive preliminary result led police to develop probable cause and demand a chemical test under the Expressed Consent Law, the reliability, calibration, and administration of that follow-up test remain fully open to challenge, exactly as in any other DUI or vehicular homicide case.

The Underlying Charges Haven’t Changed

Magnus’ Law doesn’t create any new crime. A fatal or injury-causing crash involving impairment is still prosecuted under Colorado’s existing vehicular offenses — vehicular homicide under C.R.S. § 18-3-106 (a class 4 felony, rising to class 3 if the driver was impaired) and vehicular assault under C.R.S. § 18-3-205 (a class 5 felony, rising to class 4 if impaired).

What changes is simply how much evidence the state is now positioned to gather at the scene — which makes early, aggressive review of the stop itself more important, not less.

Quick Reference: The Magnus’ Law Breath-Test Mandate

Element Detail
Statute SB26-132, amending C.R.S. § 42-4-1301
Effective date August 12, 2026, 12:01 a.m.
Trigger Crash causing death or suspected serious bodily injury
Required conditions Reasonable suspicion the driver was at fault; driver not seriously injured; officer lacks probable cause for an admissible test
Nature of the test Voluntary; refusal carries no license penalty
Admissibility Neither the result nor a refusal is admissible in court
What it can lead to Probable cause for arrest or a request for further, admissible chemical testing
Exceptions Officer’s first contact more than 2 hours after the crash; or driver left before officials knew of the death/injury

This table summarizes the statute’s core mechanics for general orientation only and is not a substitute for case-specific legal advice.

Key Takeaways

  • Magnus’ Law requires officers to offer — never compel — a preliminary breath test to a suspected at-fault driver after a fatal or serious-injury crash, closing the evidentiary gap that let the driver who killed Magnus White avoid a DUI charge.
  • The test remains voluntary, and neither a positive result nor a refusal can be used directly as evidence of guilt in court.
  • The mandate has firm limits — a two-hour contact window and a scene-departure exception — that make precise timelines a central defense issue in any case arising from it.
  • A positive preliminary result can still lead to an arrest and a demand for an admissible chemical test under Colorado’s separate Expressed Consent Law, where the usual evidentiary challenges still apply.

The law creates no new crime; vehicular homicide and vehicular assault charges are still governed by their existing statutes, but the evidence supporting them at the scene of a crash will now look different going forward.

FAQFAQs (Frequently Asked Questions)

What are the new breath test offer rules coming into effect in 2026?

Starting in 2026, many jurisdictions are tightening and clarifying the rules around when police must offer a breath test after serious or fatal crashes. These changes include mandatory chemical testing by statute in fatal or serious-injury crashes, stricter refusal penalties, and streamlined procedures for officers to obtain samples, aimed at reducing legal gray areas and improving prosecution.

What is the difference between a roadside screening breath test and an evidentiary breath test?

A roadside screening breath test (pre-arrest) is a quick, often optional preliminary check that may not be admissible in court and helps establish probable cause. An evidentiary breath test (post-arrest or at a station) is the formal test tied to implied consent laws, used as key evidence in court, and refusal typically triggers license suspension.

Why do the new breath test rules focus on fatal and serious injury crashes?

Fatal and serious injury crashes require swift chemical testing because alcohol and some drugs metabolize quickly. Officers face chaotic scenes with multiple responsibilities, so lawmakers aim to reduce delays, clarify officers’ authority, impose harsher consequences for refusals, and ensure evidence remains strong for prosecution to save lives and improve legal outcomes.

How will refusal of chemical testing be treated differently under the 2026 reforms?

Refusal penalties will become more severe in fatal- or serious-injury crash scenarios. This includes longer automatic license suspensions, refusal being considered an aggravating factor at sentencing, the admissibility of refusal as evidence of consciousness of guilt, and, in some places, the creation of separate crimes for refusal under these circumstances.

Will police be able to require blood tests without a warrant under the new laws?

Generally, courts treat blood draws as more intrusive than breath tests. While reforms push for ‘breath first‘ when possible, they also establish expedited warrant procedures for blood tests when breath testing is not feasible. It is not about universally allowing warrantless blood draws, but about streamlining legal processes to obtain warrants quickly when needed.

What should drivers expect if involved in a fatal or serious injury crash starting in 2026?

Drivers involved in such crashes should expect that chemical testing will likely be mandatory by law. Refusing testing can lead to immediate penalties, including license suspension and criminal charges. Officers may have clearer authority to request breath tests first and obtain warrants quickly for blood tests if necessary, aiming for timely collection of evidence.

Defending Against The “Blacked Out” Rape Victim Under Colorado Law

Summary and Conclusion – Magnus’ Law – Key Points

1. Purpose and Background

Magnus’ Law was enacted in response to a fatal crash where a driver suspected of impairment was not tested at the scene, resulting in a missed opportunity to gather critical evidence. The law aims to close this evidentiary gap in DUI and vehicular homicide cases by mandating timely preliminary breath tests at serious crash scenes.

2. What the Law Requires

Officers must offer a voluntary preliminary breath test to a suspected at-fault driver after a crash causing death or suspected serious bodily injury, but only if:

The officer has reasonable suspicion the person was the at-fault driver. The driver is not seriously injured or in need of immediate medical attention. The officer does not already have probable cause to demand an admissible chemical test under Colorado’s Expressed Consent Law.

3. Advisement and Voluntariness

Officers must clearly advise the driver that:

The test is voluntary. The request is due to involvement in a serious crash. Neither the result nor a refusal can be used against them in court. A positive result may lead to further admissible testing or arrest. Refusing the test has no effect on their driver’s license.

4. Limits and Exceptions

The offer is not required if:

The officer’s first contact with the driver is more than two hours after the crash.The driver left the scene before law enforcement knew of the death or serious injury. The test remains voluntary and inadmissible as direct proof of guilt in court.

5. Relationship to Existing Law

Magnus’ Law applies before an arrest, filling a gap not covered by Colorado’s Expressed Consent Law (which governs post-arrest chemical testing). It does not create new crimes or change penalties for vehicular homicide or assault; it only changes evidence-gathering procedures at the scene.

6. Defense and Legal Implications

Colorado criminal defense attorneys should scrutinize whether officers followed the advisement script and whether the two-hour or scene-departure exceptions apply. Refusal to take the test cannot be used as evidence of guilt. A positive preliminary result can lead to further testing, but the reliability of subsequent tests can still be challenged in court.

7. Effective Date – Magnus’ Law took effect on August 12, 2026.

If You’re Facing a Colorado DUI, Vehicular Assault, or Vehicular Homicide Charge

Whether Magnus’ Law applied correctly to your stop — and what happened before and after any breath test was offered — can meaningfully change how your case is defended. If you’ve been charged with a crime arising from a serious or fatal crash in Colorado, the specifics of the officer’s conduct at the scene deserve a close, early review.

This article is provided for general informational purposes only and does not constitute legal advice. Reading this article does not create an attorney-client relationship between you and The Steinberg Colorado Criminal Defense Law Firm. Laws change, and the application of law to specific facts varies from case to case — consult a licensed Colorado attorney about your particular situation. This is attorney advertising.

Colorado Criminal Law – What Colorado’s New Breath-Test Rule Means for DUI and Vehicular Homicide Cases: The Magnus Law

The reader is alerted that Colorado criminal law, like criminal law in every state and at the Federal level, changes constantly. The article above was accurate when it was drafted, but it cannot account for changes that occurred after it was uploaded.

BEST-STANDING-CHOICE-200x300ABOUT THE AUTHOR: H. Michael Steinberg – Email the Author at: hmsteinberg@hotmail.com

A Denver, Colorado Criminal Defense Lawyer – or call his office at 303-627-7777 during business hours – or call his cell if you cannot wait and need his immediate assistance – please call 720-220-2277.

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You should be careful to make a responsible choice when selecting a Colorado criminal defense lawyer. We encourage you to “vet” our firm. Over the last 40 years – by focusing ONLY on Colorado criminal law – H. Michael has had the necessary time to commit to the task of constantly updating himself on nearly every area of criminal law, including Colorado criminal law and procedure and trial and courtroom practice.

H. Michael works hard to deliver the best possible results for his clients, both in and out of the courtroom. He has written extensively on Colorado criminal law and continues to do so, and he hopes this article helps you in some small way.