Colorado implied-consent law: refusing a breath / blood test triggers automatic license suspension (1 year (1st refusal — designated as 'persistent drunk driver')) regardless of DUI outcome. Criminal refusal: Designated 'persistent drunk driver' triggers ignition interlock + alcohol education even without DUI conviction.
Published May 6, 2026
## Refusing the breath test in Colorado
One of the most consequential decisions in a DUI stop happens BEFORE you've been charged: whether to take the breath / blood test. Colorado, like all states, has an "implied consent" law — by getting a driver's license, you've consented to chemical testing if lawfully arrested for DUI.
### Colorado implied-consent framework
- **Implied consent law:** Yes (Express Consent)
- **Refusal license suspension:** 1 year (1st refusal — designated as 'persistent drunk driver')
- **Criminal refusal:** Designated 'persistent drunk driver' triggers ignition interlock + alcohol education even without DUI conviction
## What "implied consent" actually means
Implied consent doesn't mean you can't refuse — you CAN refuse. But refusal triggers automatic civil consequences:
- **License suspension** (administrative — by DMV, separate from criminal case)
- **Refusal admissible at criminal trial** in most states (jury can hear about it and infer guilt)
- **Sentencing enhancement** — convicted DUI defendants who refused often face longer mandatory jail and license periods
- **In some states**, refusal is itself a separate crime
## Birchfield v. North Dakota (2016)
**Birchfield v. North Dakota (2016)** — Supreme Court held that:
- **Breath tests** can be conducted incident to arrest WITHOUT a warrant — no Fourth Amendment problem; criminal penalties for refusal are constitutional
- **Blood tests** generally REQUIRE a warrant — Fourth Amendment protected; criminal penalties for refusal are UNCONSTITUTIONAL
After Birchfield, many states stopped criminalizing blood-test refusal but kept criminal penalties for breath-test refusal. License consequences for either remain valid.
## Two types of breath tests
**1. Preliminary Breath Test (PBT) at the roadside.** Often a small handheld device. In most states:
- Result is NOT admissible at trial
- Used for probable cause to arrest only
- Refusal of PBT typically has no consequences (or minor ones)
**2. Evidentiary breath test at station.** Larger machine (Intoxilyzer, Datamaster, etc.). After arrest:
- Result IS admissible at trial
- Refusal triggers implied-consent consequences
- This is the test that matters
Don't confuse the two. Refusing the roadside PBT is generally fine; refusing the station-house evidentiary test is the one with consequences.
## To take or refuse — strategic considerations
**Taking the test:**
- ✓ Avoids automatic refusal license suspension
- ✓ Avoids refusal admission at trial
- ✓ Avoids being designated a refuser for sentencing
- ✗ Provides direct evidence of BAC if you're over the limit
- ✗ High BAC supports DUI charge
**Refusing the test:**
- ✓ Eliminates direct BAC evidence
- ✓ Forces prosecution to prove impairment by other evidence (FSTs, observations, driving)
- ✗ Automatic license suspension regardless of DUI outcome
- ✗ Refusal can be argued as consciousness of guilt
- ✗ Sentencing enhancement if convicted
- ✗ Possible separate criminal charge
Generally:
- **If you're sober** — take the test (it'll prove sobriety)
- **If you're moderately drunk** — refusing may help if state's penalties for refusal are less than enhanced DUI penalties
- **If you're very drunk** — refusing often makes sense
BUT this is hard to gauge in the moment, often after a few drinks. Pre-decisions matter — many DUI attorneys recommend that their clients always take the breath test (better than no evidence at all to fight).
## Blood vs breath
**Blood tests:**
- More accurate than breath
- Require warrant (post-Birchfield) or true consent
- Can detect drugs, not just alcohol
- Can be retested by defense
- Take days/weeks to get results
**Breath tests:**
- Less accurate; subject to calibration / interference challenges
- Result available immediately
- Cannot detect drugs
- Can't be retested by defense
If officers use a warrant for blood after refusal of breath, you can't refuse — refusal of the warrant is contempt or worse.
## Administrative license suspension hearings
Most states have a **separate administrative process** for license suspension after refusal:
- **Tight deadline** to request hearing (often 7-30 days from arrest)
- **Lower burden of proof** than criminal trial (preponderance of evidence)
- **Limited issues** — typically just whether the stop, arrest, and refusal warning were proper
- **Result independent of criminal outcome** — you can win the criminal case and lose your license, or vice versa
Missing the hearing deadline = automatic license suspension by default.
## What you should do
If you've been arrested for DUI in Colorado — whether you took the test or refused — call a DUI defense attorney IMMEDIATELY. The deadlines for license-hearing requests are short (sometimes just 7-15 days). Most Colorado DUI attorneys offer free initial consultations and can quickly assess both the criminal case and the administrative case.
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*This guide is general information about Colorado law as of early 2026 and is not legal advice. Implied-consent law has many edge cases (medical conditions, language barriers, equipment failures, warrant procedures). Talk to a licensed Colorado criminal-defense attorney about your specific case.*
This guide is for general information only and does not constitute legal advice. Laws change and outcomes depend on your specific situation — talk to a licensed attorney before acting on anything you read here.