How Maryland Handles DUIs for Medical Marijuana Patients

 Posted on September 25, 2025 in DUI

Maryland residents with valid prescriptions for medical marijuana may assume they are safe from DUI charges so long as they are using the drug legally, but this is not always true. While alcohol has a clear legal limit in the form of breathalyzer or blood BAC readings, there is no specific THC threshold for marijuana as it pertains to impaired driving.

Practically speaking, this means that even if you are legally using marijuana and you do not believe you were driving erratically, the police and prosecutor can claim impairment and charge you with DUI (Section 21-902). Speaking to a knowledgeable Silver Spring, MD DUI lawyer who can help you understand the gap between medical marijuana laws and DUI enforcement can be beneficial.  

What Are Maryland’s Medical Marijuana Laws?

Medical marijuana is governed by the Maryland Medical Cannabis Commission (MMCC). A medical marijuana card allows up to 120 grams of cannabis flower and/or 36 grams of THC in infused products. A qualifying patient may home-cultivate no more than four marijuana plants per residence.

As of March 2025, there were an estimated 100,665 valid medical marijuana licenses in the state. There are certain employment protections for qualifying patients, although employers are not required to permit or accommodate the use, consumption, possession, transportation, sale, or growing of cannabis in the workplace.

DUI Standards in Maryland

DUI applies in the state of Maryland when a person is impaired "to any extent" by drugs or alcohol. This is a very broad definition, and determining whether a person is impaired when no set THC limit exists in Maryland is highly subjective. The prosecutor relies on observations by the police officer, field sobriety tests, and the expertise of drug recognition experts to build their case.  

A drug recognition expert is a specially trained officer who follows a standardized 12-step process to evaluate suspected drug-impaired drivers. While the drug recognition expert’s testimony can be very influential in DUI drug prosecutions, the process has inherent limitations. Some of the steps used include:

• A check of vital signs, including body temperature, blood pressure, and pulse.
• Checking pupil size under different light levels
• Muscle tone assessment
• Statements from the suspect regarding drug history and recent drug use.
• The evaluator’s opinion
• Laboratory analysis of blood or urine.

The laboratory analysis for marijuana is largely considered useless, since the drug can stay in a subject’s urine for five to 30 days, in the blood for up to 24-48 hours, and in the hair follicles for up to 90 days. A faster metabolism and lower body fat help clear THC from the system more quickly, as it is stored in fat cells.

The more frequently and heavily an individual uses marijuana, the longer it will remain in his or her system. In short, TCH remains detectable in the body long after impairment has faded. In some cases, a police officer may misinterpret lawful use as evidence of impairment.  

Potential Penalties of a Marijuana DUI and Defenses

If the prosecutor makes the case against a defendant for a marijuana DUI, he or she will face the same penalties as for an alcohol DUI. These penalties include up to one year in jail, a maximum fine of $1,000, 12 points on the driver’s license, and the potential for a 180 to 270-day license suspension. Some of the more common defenses for a marijuana DUI include:

• Emphasizing the absence of driving behaviors consistent with impairment
• Proving a lack of actual impairment despite positive THC results
• Challenging DRE testimony and the reliability of field sobriety tests.
• Highlighting Maryland’s lawful prescription use of cannabis

Contact a Montgomery County, MD Criminal Defense Lawyer

Even if you have a medical marijuana prescription, it may not protect you from being arrested for DUI, and may even complicate your defense. As quickly as possible after you are charged, contact an experienced Silver Spring, MD DUI attorney from The Law Offices of Gerstenfield & Demirji, PC.. We will begin building a solid defense on your behalf and will aggressively defend your charges. Our attorneys are compassionate, have good relationships with prosecutors, are fluent in Arabic and Spanish, and are available 24/7. To schedule your free consultation, call 301-589-9500.