Maryland legalized recreational marijuana in 2023 — but that doesn’t mean you can smoke and drive. A Maryland marijuana DWI charge carries the same criminal penalties as an alcohol-based DUI, can result in the same license suspension, and can follow you on your record the same way. What makes cannabis DWI cases fundamentally different — and far more legally complex — is that Maryland has no established legal limit for THC the way it has a .08% BAC threshold for alcohol.
No legal limit means prosecutors must prove impairment through other means. And that means the evidence in a Maryland marijuana DWI case is far more subjective, far more challengeable, and far more dependent on the testimony of specialized officers called Drug Recognition Experts.
Attorney Michael Taylor explains how these cases are built — and how they are fought.
Can You Get a DUI for Marijuana in Maryland?
Yes — and the answer surprises many people who assume legalization created a free pass to drive after using cannabis.
Under Md. Code Ann., Transp. § 21-902, it is unlawful to drive or attempt to drive a motor vehicle while impaired by any drug — including marijuana. The statute does not require proof of a specific THC concentration. It requires proof that the driver was impaired to a degree that affected their ability to drive safely.
Maryland law creates two distinct charge levels:
- Driving While Impaired by Drugs (DWID) — a lesser charge, typically a misdemeanor, where impairment is present but not to the full level of intoxication
- Driving While Intoxicated by Drugs (DWID — full intoxication standard) — a more serious charge requiring proof that the driver was so impaired they could not drive safely
Both charges are criminal. Both can result in fines, license suspension, jail time, and a permanent criminal record. The absence of a legal THC limit doesn’t protect drivers — it just changes how prosecutors build their case.
Why There Is No Legal THC Limit for Maryland Marijuana DWI
Unlike alcohol, where decades of research established a reliable relationship between BAC and driving impairment, THC behaves very differently in the human body:
- THC is fat-soluble — it is stored in fat tissue and released gradually over days or weeks, meaning a person can test positive for THC long after any psychoactive effects have worn off
- Tolerance varies enormously — a regular cannabis user may show high blood THC levels with minimal functional impairment; an occasional user may show lower levels with significant impairment
- No validated per se limit exists — according to the National Highway Traffic Safety Administration, no specific THC blood concentration has been reliably shown to correlate with driving impairment the way .08% BAC does for alcohol
Several states have attempted to establish per se THC limits (typically 5 nanograms per milliliter of blood), but Maryland has not. This creates a fundamentally different evidentiary landscape — one where impairment must be demonstrated through observed behavior, physical symptoms, and expert testimony rather than a simple number.
How Prosecutors Prove a Maryland Marijuana DWI
Without a legal limit, the prosecution’s case in a Maryland marijuana DWI typically relies on several layers of evidence:
Officer Observations at the Traffic Stop
The arresting officer’s testimony is the foundation. Prosecutors will present the officer’s observations of:
- Bloodshot or red eyes
- Odor of marijuana in the vehicle
- Slow or slurred speech
- Dilated pupils
- Impaired reaction time during the traffic stop
- Open marijuana or paraphernalia in the vehicle
- Admission of recent marijuana use
Critically, many of these observations are highly subjective. Bloodshot eyes can result from allergies, fatigue, or contact lenses. Dilated pupils are affected by lighting conditions. Slow speech is affected by anxiety, personality, and communication style. None of these indicators, standing alone, proves impairment to the legal standard.
Standard Field Sobriety Tests — With Serious Limitations
Officers often administer the same Standardized Field Sobriety Tests (SFSTs) used in alcohol DUI cases. But here is the problem: SFSTs were developed and validated specifically to detect alcohol impairment. The scientific basis for using them to detect marijuana impairment is significantly weaker, and NHTSA has not validated them for cannabis detection with the same rigor applied to alcohol cases.
As we discussed in our guide on Maryland Field Sobriety Test Errors, these tests are already vulnerable to challenge based on environmental conditions and physical health — challenges that apply equally or more forcefully in marijuana DWI cases.
Blood or Urine Testing
After arrest, a drugged driving lawyer MD will scrutinize any chemical testing carefully. Officers may request a blood draw to detect THC and its metabolites. The results, however, require careful interpretation:
- Delta-9-THC is the active psychoactive compound — its presence suggests recent use
- THC-COOH is an inactive metabolite that can remain in the body for weeks after use — its presence does not indicate current impairment
- A positive test showing only metabolites, without active THC, is extremely difficult to use as evidence of impairment at the time of driving
Chain of custody, lab procedures, and the qualifications of the testing analyst are all subject to challenge under Maryland Rule 5-702 governing expert testimony.
The Role of Drug Recognition Experts in Maryland Marijuana DWI Cases
This is where Maryland marijuana DWI prosecutions often hinge — on the testimony of a Drug Recognition Expert (DRE).
A DRE is a law enforcement officer who has received specialized training — certified through a program developed by NHTSA and the International Association of Chiefs of Police — to identify drug impairment through a structured 12-step evaluation protocol. In Maryland, DRE evaluations are governed by COMAR 11.22.06.
The 12-step DRE protocol includes:
- Breath alcohol test
- Interview of the arresting officer
- Preliminary examination (pulse, pupil size, general appearance)
- Eye examinations (HGN, vertical gaze nystagmus, lack of convergence)
- Divided attention tests (SFSTs)
- Vital signs (pulse, blood pressure, body temperature)
- Dark room examinations (pupil size under different lighting)
- Muscle tone examination
- Injection site examination
- Subject interview
- DRE opinion
- Toxicological examination
At the conclusion, the DRE provides an opinion on whether the subject is impaired and which drug category is responsible. In Maryland marijuana DWI cases, the DRE typically identifies the subject as impaired by a cannabis category drug.
Challenging DRE Testimony
DRE testimony is not bulletproof — and an experienced drugged driving lawyer MD will challenge it aggressively:
- DRE certification and training records — was the officer properly trained and currently certified?
- Protocol deviations — any step skipped or improperly administered undermines the entire evaluation
- Scientific validity — courts in various jurisdictions have questioned whether DRE opinions meet the Frye or Daubert standards for admissible expert testimony; Maryland courts continue to examine this under Md. Rule 5-702
- Alternative explanations — fatigue, medical conditions, anxiety, and medications can replicate many DRE indicators
- The correlation problem — even a valid DRE opinion does not establish the degree of impairment at the time of driving, particularly given THC’s variable metabolism
In the absence of a legal limit, the DRE’s opinion is often the prosecution’s most critical evidence — and it is also their most vulnerable.
Defending a Drug-Related DWI in Montgomery County
Montgomery County prosecutors have experience with Maryland marijuana DWI cases, and local law enforcement agencies have trained DREs on staff. An effective defense requires an attorney who understands both the science behind THC metabolism and the procedural requirements governing DRE evaluations and chemical testing in Maryland courts.
Attorney Michael Taylor handles drug-impaired driving cases throughout Montgomery County, Prince George’s County, and across Maryland — from challenging the initial traffic stop to cross-examining DRE witnesses at trial.
For related reading, see our guides on The Lasting Impacts of a DUI Conviction in Maryland and Digital Evidence in Maryland Criminal Cases — both directly relevant to how modern DWI cases are investigated and prosecuted.
Call the Law Office of Michael A. Taylor at 301-251-2772 or contact us here for a consultation.
