The History of DUI Law in Colorado: From “No Number” to 0.08
Colorado’s DUI laws didn’t start with a neat blood-alcohol number and a standardized breath test. Like most legal history, it’s a story of changing science, changing social attitudes, and lawmakers slowly turning “Don’t do that” into “Don’t do that… and here’s the exact decimal.” 😄
Below is a light, informative timeline of Colorado’s early impaired-driving statutes to today’s DUI, DWAI, Express Consent, and modern “per se” limits.
Quick refresher: DUI vs. DWAI in Colorado (today)
Colorado recognizes two main alcohol/drug driving offenses:
- DUI: driving when alcohol/drugs make you substantially incapable of safe driving. Colorado General Assembly
- DWAI: driving when alcohol/drugs affect you to the slightest degree—yes, that’s the actual standard, and yes, it’s as broad as it sounds. Colorado General Assembly
Fun fact: Colorado’s “DWAI” concept often surprises out-of-staters because it explicitly targets that “I’m fine—I only had a couple” zone. (The law is basically: “A slight buzz still counts.”) Colorado General Assembly
The early era: before BAC numbers (Prior to 1955)
Colorado had impaired-driving rules long before modern testing, but there was no “per se” BAC limit—meaning the state didn’t rely on a specific alcohol concentration to automatically establish intoxication. CDPSS Docs
In this period, cases leaned heavily on observations: driving behavior, coordination, speech, and other “common-sense” evidence.
Science enters the chat: presumptions arrive (1955–1972)
By the mid-1950s, Colorado law began using BAC presumptions—not automatic guilt, but legal inferences.
During 1955–1972, Colorado used:
- 0.15 as an “illegal presumption” level for DUI, and
- 0.05 tied to impairment (DWAI-style concepts). CDPSS Docs
Translation: lawmakers started treating alcohol impairment as something measurable—even if the rules weren’t as clean as today.
Lowering the bar (literally): 1973–1982
From 1973–1982, the DUI presumption dropped to 0.10, while DWAI remained at 0.05. CDPSS Docs
This matches a broader national trend: research and policy increasingly recognized that serious driving impairment can occur well below 0.15.
1983: A big turning point—“per se” DUI and Express Consent
Colorado adopts “per se” BAC (1983–1988)
Starting 1983, Colorado introduced an illegal per se BAC limit—meaning a specific number could establish the offense without needing to prove actual impairment the old-fashioned way.
- Per se limit: 0.15
- DUI presumption: 0.10
- DWAI presumption: 0.05 CDPSS Docs
Colorado also creates “Express Consent” (1983)
Colorado first established an Express Consent to test statute in 1983. CDPSS Docs
If “Express Consent” sounds like something you clicked through while installing software… you’re not wrong in spirit. By driving in Colorado, you’re deemed to have agreed to chemical testing under certain conditions—today administered through C.R.S. § 42-4-1301.1. Colorado Department of Revenue+1
1989–2003: Per se drops to 0.10
From 1989–2003, Colorado lowered the per se BAC limit to 0.10. CDPSS Docs
This era also reflects the rise of standardized DUI enforcement (and the increasing role of breath/blood testing in court).
1997: Underage drinking & driving becomes its own lane
In 1997, Colorado created the “UDD” framework—an under-21 traffic infraction for driving with a BAC at least 0.02 but less than 0.05. Colorado Law Scholarly Commons
Interesting tidbit: 0.02 can be reached faster than many people realize, especially with low tolerance or on an empty stomach—one reason this law catches families off guard.
2004–present: The modern standard—0.08 per se
Since 2004, Colorado’s per se DUI BAC has been 0.08, and the DUI presumption aligns at 0.08 (with DWAI at 0.05). CDPSS Docs
Colorado statutes today reflect that in C.R.S. § 42-4-1301 (DUI/DWAI) and related sections. Justia
2013: Marijuana “permissible inference” enters the statute
In 2013, Colorado added a permissible inference for marijuana DUIs: 5 nanograms or more of Delta-9 THC per milliliter of whole blood can support an inference of being under the influence. CDPSS Docs
Two key “legal-history” notes here:
- It’s an inference, not a perfect “per se” alcohol-style rule.
- Colorado’s own policy discussions have acknowledged the science is more complex for cannabis impairment than for alcohol. CDPSS Docs
2015: Colorado makes repeat DUI a felony
In 2015, Colorado enacted major changes under HB 15-1043, including making DUI/DWAI a felony (Class 4) for people with three or more prior convictions (i.e., a fourth offense). Colorado General Assembly
The statutory history notes an effective date of August 5, 2015. Justia
Why this history matters if you’re facing charges now
Today’s DUI case in Colorado is the product of:
- decades of shifting BAC thresholds, CDPSS Docs
- a system that treats even slight impairment as chargeable (DWAI), Colorado General Assembly
- mandatory testing rules through Express Consent, Colorado Department of Revenue
- and newer drug-impaired-driving frameworks (like THC inference). CDPSS Docs
That means small details matter: timing, testing, procedure, driving context, and how the state is trying to prove impairment.
Talk to a Colorado DUI lawyer (without judgment)
If you’re dealing with a DUI or DWAI in Colorado, Pav Law can help you understand what you’re up against and what options you may have—from DMV consequences to the criminal case.
If you’re facing a DUI, DWAI, DUID charge, you need an attorney that knows the ntact Pav Law at (719) 888-7888 to request a confidential consultation.
Legal note: This article is for general information, not legal advice. Every case is different.
Sources (Colorado law, legislative materials, and official summaries)
- Colorado Office of Legislative Legal Services, Colorado Drunk Driving Laws – Colorado Law Summary Colorado General Assembly
- Colorado Division of Criminal Justice / Office of Research & Statistics, Driving Under the Influence of Drugs and Alcohol (HB17-1315 Report) (includes BAC timeline table and Express Consent note) CDPSS Docs
- Colorado Department of Revenue, Express Consent (C.R.S. § 42-4-1301.1 overview) Colorado Department of Revenue
- C.R.S. § 42-4-1301 and statutory history notes (including HB 15-1043 effective date) Justia
- University of Colorado Law (Session Laws archive), 1997 Underage Drinking & Driving (0.02–0.05) Session Law Colorado Law Scholarly Commons
- Legislative materials discussing THC permissible inference / 5 ng/mL statebillinfo.com
