Driving Under The Influence Of Marijuana In Pennsylvania


In Pennsylvania, an individual may not drive, operate or be in actual physical control of the movement of a vehicle under any of the following circumstance if there is in the individual’s blood any amount of a:

  1. Schedule I controlled substance, as defined in the act of April 14, 1972 (P.L.233, No.64), known as The Controlled Substance, Drug, Device and Cosmetic Act;
  2. Schedule II or Schedule III controlled substance, as defined in The Controlled Substance, Drug, Device and Cosmetic Act, which has not been medically prescribed for the individual; or
  3. metabolite of a substance under 1 or 2 above.


The Federal Government classified marijuana (cannabis) as a Schedule I drug.


THC (Tetrahydrocannabinol or Delta-9-THC) is the main psychoactive compound in marijuana that produces the “high” sensation.  THC is broken down in the system and modified into molecules known as metabolites.  There are at least 80 different metabolites that are formed from THC.  Marijuana stays in the bloodstream for a short time, but THC metabolites can remain in a person’s body for days, weeks or even months.  THC detection is directly dependent on accurate testing procedures for metabolites since a drug metabolite is a reliable indicator that a person used the “parent” drug of that metabolite.


In 2016, Pennsylvania approved the use of marijuana for medical use and more than 250,000 Pennsylvania residents have received a medical marijuana license.  Despite the legal use of medical marijuana for persons prescribed the drug for pain or anxiety, a person commits a crime under Pennsylvania law if they drive with any amount of THC in their system.  This obviously presents a huge problem since an individual is susceptible to a DUI conviction even when the person is not impaired while driving.  In other words, a driver can be convicted of DUI long after the psychoactive effects of THC have worn off if any trace of marijuana or metabolite is discovered after a blood test.  This is a tricky legal issue since many scientists believe that measuring THC levels is not a reliable method of determining impairment.


Testing for controlled substances in blood is normally a two-step process.  The first step involves screening of the blood using a rapid, inexpensive procedure to presumptively determine whether a specimen contains a controlled substance or a metabolite of a controlled substance.  The second step involves another procedure to confirm the presumption.  In 2017, the Pennsylvania Department of Health implemented regulations in the Pennsylvania Bulletin (volume 34, issue 7).  For Marijuana, blood test results must show a minimum level of THC of .5 nanograms per milliliter of blood for the results to be admissible in Court.  This is a very small amount.  Any amount of cannabis metabolites at or above this level can be introduced as evidence by the prosecution for a charge of driving under the influence of a controlled substance


First offense marijuana DUI. 

  • Misdemeanor
  • Imprisonment from 72 hours to 6 months
  • Fine of $1000 to $5000
  • Alcohol highway safety school
  • License suspension of at least 18 months
  • 150 hours of community service
  • Attend victim impact panel

Second offense marijuana DUI

  • Misdemeanor
  • Imprisonment from 90 days to 6 months
  • Fine of at least $1,500
  • Alcohol highway safety school
  • License suspension of at least 18 months
  • 150 hours of community service
  • Attend victim impact panel

 Third and subsequent offense marijuana DUI

  • 2nd degree misdemeanor
  • Imprisonment at least 1 year
  • Fine of not less than $2,500
  • License suspension of at least 18 months
  • 150 hours of community service
  • Attend a victim impact panel


In many instances, a person who is pulled over for possible marijuana DUI can face other charges such as:

  • possession of drug paraphernalia
  • possession of a controlled substance
  • possession of small amount of marijuana
  • possession with intent to deliver marijuana

These charges arise from a search of the offender’s vehicle. 


The Fourth Amendment of the U.S. Constitution prohibits unreasonable searches and seizures.  In order to conduct a warrantless search of a motor vehicle for drug paraphernalia or marijuana, there must be probable cause. Probable cause can exist when a police officer can articulate a particularized justification based on the totality of the facts and circumstances for believing the individual is engaged in criminal conduct.


Generally, law enforcement needs probable cause to conduct a warrantless search of a vehicle.  In the case of Commonwealth of Pennsylvania v. Timothy Oliver Barr, II, a Judge in Lehigh County, Pennsylvania determined that law enforcement did not possess probable cause to conduct a warrantless search of the subject vehicle based solely on the odor of marijuana emanating from the vehicle.  In that case, two state troopers stopped a vehicle for violating a traffic law.  Timothy Barr was in the front passenger seat and his wife was driving the vehicle.  When the troopers approached the vehicle, they smelled marijuana.  One of the troopers advised the occupants of the vehicle that he could search the vehicle, as the odor of marijuana provided them with probable cause to conduct a warrantless search. Mr. Barr presented the trooper with a medical marijuana license, but the troopers still conducted the search of the vehicle.  The troopers found marijuana, plastic bags, and a handgun. The Commonwealth charged the defendant with possession of marijuana and for possessing a firearm without a license.  The Court held that the odor is not enough to conduct a warrantless search.  

The Court in the Barr case created a new standard.  Basically, the smell of marijuana is no longer per se indicative of a crime since individuals in Pennsylvania may have a valid medical marijuana card, which permits them to possess and ingest marijuana legally.  In other words, if someone has a medical marijuana card, then it is expected that there might be an odor of marijuana emanating from his or her person, clothes, hair, breath, and vehicle.   


The most common method by which a police officer will search a car for marijuana or drug paraphernalia is through the driver’s consent to search. If the driver gives consent to the search, and no duress was used in obtaining that consent, then the search will generally be legal. Although police officers will often attempt to convince a driver that providing consent will make things “easier” on the driver, there is little evidence that is ever the case, and a driver with marijuana or drug paraphernalia in the car has little to nothing to gain in providing consent to the officer to search the car.


If the police officer has reasonable suspicion to detain you in your car which means that the officer can point to facts which indicate you violated a law (e.g. speeding or changing lanes without a turn signal), then the officer can also seize whatever is in “plain view”.  Thus, if an officer sees drugs or drug paraphernalia sitting on your backseat or next to you without entering the car, the officer can seize those items and charge you with related crimes.


Other factors to consider in future cases include whether the smell is so overpowering that an officer may conclude that the driver has a quantity of marijuana that exceeds what is allowed.  Also, driving under the influence of marijuana is illegal in Pennsylvania, so police are still free to search the car of a driver who shows signs of impairment.  


  • Illegal stop
  • Illegal search
  • Flaws with testing


Law enforcement officials in Montgomery County, PA have begun emphasizing the issue of driving under the influence of drugs, also called drugged driving, or drug DUI.  If you have been arrested for DUI arising from marijuana or if you are charged with marijuana possession or possession of drug paraphernalia, call us today at 215-646-3980.  An attorney at The Martin Law Firm will discuss your case at no charge. 



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