You haven’t smoked since the night before, and you feel completely normal, sharp enough to drive your kids to school, alert enough to make it through a full day of work. But the officer who pulls you over for a burned-out taillight says your eyes look red, and after a few roadside questions and balance checks, he’s placing you under arrest. Now you’re sitting in the back of a patrol car outside a gas station in Aurora, headed to the station for a blood draw, and you know you didn’t do anything wrong. At Mark S. Rubinstein, P.C., I understand what it means to use marijuana legally and still end up in this position, and I step in to challenge what that blood test really proves about the day you were pulled over.
Colorado DUID Charges: What a THC Blood Result Does and Does Not Prove
A marijuana-related driving charge often hinges on one lab number, but the law is more nuanced than most drivers are told. Here is what to understand if you are facing a Colorado DUID.
- The 5 nanogram rule is a permissible inference, not a strict cutoff: a judge or jury may consider a blood level of 5 ng/mL or more of active Delta-9 THC as evidence, but it does not automatically prove guilt.
- Prosecutors still have to prove impairment, meaning your ability to drive was affected to the slightest degree for DWAI, or substantially for DUI.
- Regular cannabis users and people with a high tolerance may be affected differently by the same THC level, which can complicate how a blood result is interpreted.
- Impairment evidence goes beyond the blood test, and the way a stop, a roadside evaluation, and the testing itself were handled can be examined and challenged.
A High THC Number Is Not the Same as Guilt.
If a blood test came back with the number you keep hearing about, it can feel like your case is already decided. It is not. Colorado law treats that result as evidence a judge or jury may consider, not an automatic conviction. Mark Rubinstein has practiced law for more than 30 years, 25 of them in Colorado, and can walk you through what your result does and does not mean. Reach out for a free, confidential conversation.
Request A Free ConsultationWhat Is the 5-Nanogram Rule in Colorado DUID Cases?
Colorado law allows a permissible inference that a driver was under the influence of marijuana when an analysis of the driver’s blood shows 5 nanograms per milliliter or more of active Delta-9 THC. That means a judge or jury may consider the THC level as evidence of impairment, but the 5-nanogram level does not automatically establish guilt, and the prosecution still has to prove the charge beyond a reasonable doubt. A DUID charge based solely on this number is not an automatic conviction.
Why the 5-Nanogram Threshold Hits Regular Users Harder
The nanogram rule was written as an inference, not a strict cutoff, because THC does not affect every person the same way. A person who rarely uses cannabis might feel impaired at 2 nanograms. A daily user might feel completely normal at 8 nanograms, because their body processes THC differently than an occasional consumer’s does. This can create a real problem for regular consumers. THC metabolites can linger in the blood well after the high fades, so a legal user who hasn’t felt any effects in hours may still have active Delta-9 THC in their bloodstream. Even so, a blood THC concentration does not by itself establish how impaired a particular driver was. The state’s own guidance confirms that using cannabis legally, even for medical reasons, does not prevent an officer from arresting you for impaired driving. The difference between what the blood test shows and what other evidence shows about your ability to drive can become an important issue in a marijuana DUI case in Colorado.
What Counts as Impairment Beyond the Blood Test?
A nanogram number is only one piece of evidence. Prosecutors also rely on:
- Field sobriety tests—your performance on balance and coordination exercises during the stop;
- Officer observations—statements about your speech, eyes, driving pattern, or admissions you made at the scene;
- Drug recognition evaluations—a specialized officer’s assessment of physical signs tied to specific drug categories;
- Timing of the blood draw—the amount of time between the stop and when your blood was drawn and tested, since THC levels can shift; and
- Chain of custody—the documentation verifying that the blood sample was properly labeled, stored, and tracked from the draw to the lab.
Each of these can be challenged. A poorly administered field test, questions about an officer’s training or observations, or issues involving the collection, handling, or analysis of the blood sample may provide grounds to challenge the State’s evidence.
Can You Be Charged with Driving While High Even If You Feel Fine?
Yes. Colorado’s impaired driving law does not require you to feel high, only that your ability to drive safely was affected to the slightest degree for a DWAI charge, or substantially for a full DUI. That standard leaves plenty of room for prosecutors to argue impairment even when a driver insists they felt normal. This is exactly why allegations of driving while high, built on subjective observations, deserve the same scrutiny as the blood test itself.
How Does Tolerance Complicate a Weed DUI Defense?
Tolerance is not currently a consideration in Colorado’s nanogram rule, but it is central to why that number is only a permissible inference, not a strict per se limit, which is a legal threshold where crossing the number means you are automatically guilty by law. A defense built around tolerance and functional sobriety asks the judge or jury to look past the number and consider what the evidence actually shows about how you were driving that day. Dashcam footage, witness accounts, and the actual timeline between your last use and the stop can all support that argument. A DUI charge grounded almost entirely in a nanogram count, with little else in the record, may leave more room to challenge whether the prosecution can prove actual impairment beyond a reasonable doubt.
What Should You Do If You’re Charged with a Colorado DUID?
Don’t assume a blood test result decides your case before you’ve had a chance to challenge it. The circumstances of the stop, the timing of testing, and the other evidence of impairment all matter. Getting a defense attorney involved early can help preserve evidence and identify potential challenges to the prosecution’s case.
Felt Fine Behind the Wheel but Charged Anyway? Let’s Talk.
If you use cannabis regularly and legally, and you felt fine when you were pulled over, a drugged driving charge can feel unfair and confusing. You should not have to face it feeling judged before anyone has heard your side. Mark Rubinstein handles each case personally and will review the evidence against you, so you can understand your options and decide what to do next.
Talk To Mark RubinsteinWhy Turn to Mark S. Rubinstein, P.C., to Help with Your DUID Charge?
I have spent more than three decades practicing law, 25 of those years right here in Colorado, and I have built my practice entirely around litigation. I earned Avvo’s Clients’ Choice Award in 2022 and 2023, reflecting a five-star rating across 69 reviews, and I am admitted to practice in Colorado’s courts, including the Colorado Court of Appeals, and in federal court in the Tenth Circuit. I also speak Spanish, so language is never a barrier to understanding your rights. I believe that people facing serious legal trouble deserve a defense grounded in real experience, and I bring that same commitment to every DUID case I take on.
Talk to Mark S. Rubinstein, P.C. About Your Case
A DUID charge can put your license, your record, and your future on the line, but the State’s case is not as airtight as a blood test might suggest. Reach out to Mark S. Rubinstein, P.C., for a consultation to talk through what happened and your options. I personally handle my clients’ cases and can examine the State’s evidence rather than treating the 5-nanogram result as the end of the analysis.
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