Medical Marijuana in Colorado

Your card is not a DUI defense. The statute says so directly.

This is the single most dangerous misconception among medical marijuana patients in Colorado. Possessing a valid medical marijuana card is not a defense to a marijuana DUI. The statute states it in plain language: possession of a medical marijuana license “is not a defense against the charge of driving under the influence or while ability impaired.”

Colorado law creates a “permissible inference” of impairment if your whole blood shows five nanograms or more of delta-9-THC per milliliter. That threshold is where the science and the law collide, and it is exactly where a defense is built.

Unlike alcohol, THC blood levels do not track impairment. Delta-9-THC spikes within the first fifteen minutes of use and generally falls below 5 ng within about three hours, while the actual “high” can last longer.

Worse for regular medical patients: chronic users can carry active delta-9-THC in their blood for days after use, long after any impairing effect is gone. A daily medical user can be stone-cold sober and still test over 5 ng.

Two things work in your favor, and a prosecutor knows both:

• Your card alone cannot be used against you at the roadside. Mere possession of a valid registry card “shall not, in the absence of other contributing factors, constitute probable cause” to demand a blood test.
• Frequent medical users can present expert testimony to rebut the inference, showing the jury that a number on a lab report is not the same as impairment behind the wheel.

That is a defense a former prosecutor is built to run, because he knows how the state tries to make that number look like proof.

The possession limit you can still exceed as a patient

A registry card does not give you unlimited possession. As a medical patient you can possess up to two ounces of marijuana and buy up to two ounces, eight grams of concentrate, or products containing up to 20,000 milligrams of THC in a single day. Home growers face a separate cap: no more than 16 plants on a residential property unless your local jurisdiction expressly allows more.

Cross the cultivation line and the penalties climb fast, from a petty offense above 12 plants to a level 4 or level 3 drug felony on a second offense involving larger grows.

Overrun any of these, or get caught with quantities, packaging, or circumstances that point past personal medical use, and the card stops being a shield. Product bought legally at a dispensary is still evidence of a crime the moment the amount says distribution. Concentrates and edibles complicate this further, because THC weight is measured differently than flower and patients routinely misjudge where the legal line sits.

One wrong turn onto federal land erases your card entirely

This is the trap that catches Colorado Springs residents more than anywhere else in the state. Marijuana remains fully illegal under federal law, and your Colorado registry card means nothing on federal property.

Colorado Springs is surrounded by it: the Air Force Academy, Fort Carson, Peterson Space Force Base, and Schriever Space Force Base. Drive onto any of them with cannabis in your car, legal or not under state law, and you are now facing a federal possession charge where your red card is not merely useless, it does not exist as a concept.

Federal officers do not recognize state medical authorization. Military families on PCS orders and anyone commuting to a base are at the highest risk here.

Firearms: the question on Form 4473 that turns your card into a felony admission

If you use medical marijuana and you own or want to buy a gun, you have a federal problem most people never see coming. ATF Form 4473, the form every firearms buyer must complete, asks whether you are an unlawful user of marijuana. Because marijuana is federally illegal, a medical marijuana patient who answers honestly is denied the purchase, and a patient who answers “no” to buy the gun has just committed a federal felony by lying on the form.

Colorado has not fixed this, and not for lack of trying. In 2019, state legislators introduced a bill (SB19-093) specifically to protect the firearm rights of lawful medical marijuana users. It was postponed indefinitely in committee and died. There is no Colorado carve-out. Federal law prohibits marijuana users from possessing firearms at all, regardless of state medical status, and that conflict can surface during any unrelated arrest, traffic stop, or background check.

Employment and custody: legal use, real consequences

Colorado is an at-will employment state, and your card does not protect your job. Employers can enforce zero-tolerance drug policies and terminate you for a positive test even when your use is legal, medical, and off-duty. This is the same fault line covered in our post on employment consequences of a DUI : legal conduct off the clock can still end a career.

In custody and divorce proceedings, an opposing party will use documented medical marijuana use as an argument about fitness. The card that legitimizes your medicine in one courtroom becomes an exhibit against you in another.

How a former prosecutor takes these cases apart

Every one of these situations shares a structure: the state has a number, a form, a lab result, or a policy it wants to treat as automatic proof. It rarely is.

Jeremy Loew built cases like these from the prosecution side in El Paso County before he started dismantling them. That means he knows how the state establishes the 5 ng inference, where blood-draw procedures and lab handling break down, how “probable cause” from a traffic stop gets stretched, and how the gap between a THC number and actual impairment gets exposed in front of a jury.

Knowing how the case is assembled is what lets him take it apart. If you are also facing a straight possession charge, see our Colorado drug possession guide.

If your legal medicine has turned into a criminal charge, do not assume the card settles it. It usually does the opposite.

Contact the Law Office of Jeremy Loew for a consultation about your marijuana-related charge in Colorado Springs and El Paso County.

Frequently Asked Questions

Does my Colorado medical marijuana card protect me from a DUI?

No. The statute expressly states that a medical marijuana license is not a defense to driving under the influence or while ability impaired.

Can I be charged for marijuana on the Air Force Academy or Fort Carson?

Five nanograms of delta-9-THC per milliliter of whole blood creates a permissible inference of impairment. It is not an automatic conviction, and it can be challenged, especially for regular medical users whose blood retains THC long after any impairment.

What is the THC limit for driving in Colorado?

Five nanograms of delta-9-THC per milliliter of whole blood creates a permissible inference of impairment. It is not an automatic conviction, and it can be challenged, especially for regular medical users whose blood retains THC long after any impairment.

Can I own a gun if I have a medical marijuana card?

Under federal law, no. Marijuana users are prohibited from possessing firearms, and answering the ATF Form 4473 marijuana question falsely to buy one is a federal felony.

Can I be fired for legal medical marijuana use in Colorado?

Yes. Colorado is an at-will state and employers may enforce zero-tolerance policies even for legal off-duty use.