Legal Blog

In Pennsylvania, you can get a DUI for being under the influence marijuana. If a blood test reveals that you have one nanogram of THC in a one-milliliter sample, you could get convicted. While there is still no scientific consensus regarding the amount of cannabis one needs to ingest for impairment to occur, Pennsylvania’s government assumes that even the smallest detectible amount of THC is enough to affect a driver’s psychomotor skills, attention, lane tracking, and cognitive function.

Marijuana Breathalyzers Are in the Prototype Stage

Several companies and scientific research projects are developing prototypes for marijuana breathalyzers that the police could use against DUI suspects. For States like Pennsylvania with a basically zero THC tolerance, such devices might be used in DUI cases against allegedly stoned drivers. But even then, DUI defense lawyers can still challenge the use of these devices, just like they do for the police’s use of breathalyzers in alcohol DUI cases.

On the other hand, in states like Montana, where a driver can have up to five nanograms of THC per milliliter of blood, marijuana breathalyzers will be of little use to law enforcement. This is because no current or foreseeable method can accurately detect varying amounts of THC in a person’s breath.

Marijuana Breathalyzers Can’t Detect Specific THC Amounts

At Washington State University, a team of researchers are attempting to develop a portable THC detection mechanism that uses the same principle behind the explosives detection devices used in airports. Through a technique called ion mobility spectrometry, their breathalyzer might detect the presence of THC by analyzing how the ions in the suspect’s breath respond to an electric field.

Lifeloc, a company that currently produces alcohol breathalyzers, is also trying to design an accurate marijuana breathalyzer. They have been open about the difficulties they face. According to Lifeloc’s CEO, their current prototype sometimes requires a person to blow twenty times before an accurate reading appears.

Alcohol breathalyzers work because the amount of alcohol on a drunk person’s breath is sufficient to be easily detected by a testing device. But after someone smokes marijuana, they have a much smaller amount of THC in their breath, which machines have a tough time detecting.

A company called Cannabix from Vancouver has patented a technology for its own marijuana breathalyzer, but they have yet to put a functional product on the market. Cannabix has not yet disclosed what method they use to detect THC, but their product is not designed to tell what amount of THC is in a driver’s system.

How Would Marijuana Breathalyzers Affect DUI Cases?

What all this means is that no ones knows when and if the police will start using marijuana breathalyzers. Even if they do, marijuana breathalyzers will not be a silver bullet in the prosecution of stoned drivers. The police will need probable cause to use the device. Absent the strong smell of marijuana, other supposed symptoms of impairment that might justify the use of the device such as red eyes, delayed reactions, and a relaxed demeanor can all have innocent explanations.

Even evidence from alcohol breathalyzers can be suppressed from DUI cases because of its lack of reliability. In 2013, the Pennsylvania State Police had to temporarily suspend the use of its Intoxilyzer 5000 breathalyzers after a court ruling determined that the device was too inaccurate to substantiate a DUI charge. The same tactic would hypothetically be available in cases involving marijuana breathalyzers, which for now seem much less reliable than alcohol breathalyzers.

Fienman Defense is a Philadelphia law practice dedicated to ensuring that everyone gets a fair chance when passing through the criminal justice system. Call us today at (215) 839-9529 and we can provide you with a free and confidential consultation regarding your DUI or other criminal case.