Marijuana is currently legal in twenty states for medical purposes. There is a push to have the state of Florida join the group.
Advocates say marijuana has a variety of medical benefits. Law enforcement officers know it can also cause impairment.
Sergeant Troy Morgan is part of the DUI enforcement squad with the Hillsborough County Sheriff's office. Sgt. Morgan says detecting marijuana impairment presents unique challenges.
"Marijuana or any narcotic of any type, whether it's marijuana or, you're not going to have the indicators that you would have with alcohol,"said Sgt. Morgan.
Video from a cruiser dashcam shows a deputy administering a field sobriety test to a man who had fallen asleep in his car in a parking lot. The man admitted he had taken Xanax, and tests later showed he had also smoked marijuana.
Still Morgan and other law enforcement officers say they are trained, and have a variety of tests that can determine the level of impairment. Morgan says the difficulty is getting those cases to trial, and convincing a jury that someone is impaired after using marijuana.
"We cannot quantify the marijuana and or any other narcotic and which does make it difficult," said Sgt. Morgan.
In Florida a driver is considered to be legally impaired if they have a level of .08 of alcohol in their system at the time of arrest. There is no similar standard when it comes to marijuana.
"There is not a line in the sand with marijuana or any type of narcotic," said Sgt. Morgan.
Still Morgan says there are proven signs that show someone is an impaired driver, even if they have not been using alcohol.
"They are lethargic in their movements, fumbling fingers, eyes are glassy."
The National Highway Traffic Safety Administration has developed a series of tests that are designed to test the level of impairment.
By now, many people are familiar with the test.
Drivers are asked to walk on a straight line, putting one foot in front of the other in a heel to toe move. Drivers are then asked to stand on one foot, holding the other foot off the ground for thirty seconds.
Coupled with other indicators, officers use these tests to determine if a driver is impaired and based on their observations, they can make an arrest.
In many cases, these tests and the interaction and conversations between the driver and officer are now recorded on video. The recordings can be used in court by prosecutors and the defense.
Sgt. Morgan says, it can be difficult to convince prosecutors to go after a DUI case, if the driver has only been smoking marijuana.
"In a lot of cases, not every case, but a lot of cases, because we cannot quantify the level of impairment or that was the substance that caused the impairment at that particular time, the case may not be filed on, or it could be reduced,"said Sergeant Morgan.
Defense attorney Jason Rogozinski says he would have a number of questions for a law enforcement officer in court who is testifying in a DUI case involving marijuana.
"Well my question would certainly be, well, when were they smoking marijuana? Was it now, was it ten days ago, was it 15 days ago, was it ten minutes ago," said Rogozinski.
Rogozinski says the same problem exists currently when someone is pulled over and they've been taking prescription drugs.
Rogozinski says if marijuana is legalized in Florida it may be difficult for law enforcement to prove someone is impaired at the moment they were seen driving, because marijuana can be detected in a person’s system for days or even weeks after they use it.
"I think that is one of the issues that is going to come up. How are they going to prove that they are under the influence of marijuana at the time of driving," said Rogozinski.
Sgt. Morgan says his officers will do what they are trained to do, and take impaired drivers off the streets to keep everyone else safe.
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