Driving Under the Influence of Drugs Q & A

Effects of Drugs on Driving
September 18, 2016
New Roadway Safety Guide
September 18, 2016

Driving Under the Influence of Drugs Q & A

  • Driving under the influence of drugs (DUID) has become a significant problem worldwide.
  • Drugged drivers are less frequently detected, prosecuted, or referred to treatment compared with drunk drivers.
  • There is a lack of uniformity or consistency in the way the 50 U.S. states approach drugged drivers.
  • Current laws in most U.S. states make it difficult to identify, prosecute, or convict drugged drivers.
  • Too few police officers have been trained to detect drugged drivers.
  • Per se DUID laws are feasible and represent a good strategy for dealing with drugged drivers.
  • Per se DUID laws can assist in the prosecution of DUID.

Why Support a Zero Tolerance Per Se Drugged Driving Bill?

Today it is legal to drive in Florida or other states with mind-altering illegal drugs in your body if they do not have a 0 per se law. Most states have a zero tolerance per se law for alcohol among drivers who under age 21 who have a blood alcohol concentration (BAC) of .02 or higher, but this does not include other drugs.

The law prohibits driving under the influence or being impaired by drugs, but the burden of proof that the driver is under the influence or is impaired is sometimes difficult to meet when it should not be.

Here’s why –

  • Drug impairment is different from alcohol impairment. Law enforcement officials trained to recognize alcohol impairment may not be able to recognize drug impairment. To remedy this, some states have trained Drug Recognition Experts (DREs). Currently there are 49 states in the Drug Evaluation and Classification Program (DECP) and approximately 7,000 DREs throughout the U.S. There are not nearly enough DREs to cover the increasing drugged driving in every state. Moreover, given the time required to get a trained DRE on the scene of a DUID case, an impaired driving suspect’s impairment subsides and/or drug levels decline.
  • Florida currently has 236 DREs in many areas, particularly populated areas, yet the need remains for DREs in over half of all counties. Manpower shortages and budget limitations often deny many agencies from participating in the DECP to train new DREs.
    • A DRE must complete all 12 steps of an evaluation in order to be able to testify in court that, in his/her opinion, the suspect was driving under the influence of drugs. This procedure takes up to one hour, during which time the suspect’s impairment continues to decline, unless they are using a roadside oral fluid device.
  • Impaired driving suspects who are injured or are being cared for by paramedics cannot be assessed by a DRE, sometimes until well after their impairment subsides.
  • Uncooperative impaired driving suspects may not be assessable at all.

Behavioral assessments to determine whether or not a driver is under the influence of alcohol or a drug is subjective, making the resulting court cases difficult, expensive, and unpredictable. That is why states began enacting laws that enabled objective laboratory tests to supplement behavioral assessments to provide toxicological support for the driver’s demonstrated impairment. Such laws are usually referred to as per se laws, since the laboratory test per se (by itself) designates a violation of the law. The first such law was passed by Indiana for alcohol in 1939. The first drug per se law was passed by Arizona in 1990. Currently 18 states have some form of the per se standard for drugs. We need to demonstrate zero tolerance for drugged drivers.

How are drug per se laws enforced?

Drug per se laws vary by state. A law officer must have reasonable suspicion that a person has committed, is committing or is about to commit a crime in order to stop a driver (e.g. erratic driving, traffic infraction, crash) before an investigation for drug use can begin. The officer will perform a Standardized Field Sobriety Test (SFST) which provides further behavioral evidence of impairment. If an officer determines there was probable cause based upon the evidence, the driver is arrested for impaired driving, transported to the police station and tested for alcohol. Typically if a driver has an illegal blood alcohol concentration (BAC), at or above 0.08 g/dl, a drug test is not administered, even though drugs may have contributed to driver impairment. If a driver does not have an illegal BAC, a drug test may be administered, using either urine or blood samples, or both, depending upon the law. Unfortunately, drug testing is not commonly done on impaired driving suspects. Without drug testing of these drivers, many cases are then dismissed, leaving the drugged driver free to continue his/her dangerous behavior.

If laboratory test reveals the presence of drugs in the driver’s system in concentrations that are prohibited by law, then the driver is charged with driving under the influence of that drug (DUID) or (DWI). The presence of the drug or drugs is per se evidence of drugged driving.

What about medical marijuana?

Marijuana is not approved by the Food and Drug Administration (FDA) nor is it distributed through professional pharmacies and cannot be prescribed. Marijuana use remains a federal violation of the regulations by the U.S. Department of Transportation for all commercial drivers, even in states which permit medical marijuana. States with medical marijuana may address this issue with their own laws.

The following states have per se drugged driving laws and medical marijuana laws:

  • Arizona – exempts “a person using a drug prescribed by a medical practitioner” from its per se clause. This does not exempt medical marijuana, since it is not prescribed.
  • Rhode Island – there are no provisions to exempt medical marijuana or prescribed drugs.
  • Delaware – per se law applies only to “unlawful” use of prohibited substances.
  • Michigan – no exceptions provided for medical marijuana
  • Nevada – Establishes a permissible limit of 2 ng/ml in whole blood for delta-9-THC and 5 ng/ml in whole blood for carboxy-THC.
  • Colorado established a 5 ng/ml permissible blood limit for delta-9-THC.
  • Washington has a 5 ng/ml per se limit for THC in adults and zero tolerance for THC in minors.
  • Montana has a 5 ng/ml per se limit for THC in all drivers.

What if a driver takes a prescription medicine and drives?

Patients need to discuss with their prescribing physician and pharmacist about the possible impairing effects of the drugs prescribed to them and read all caution labels before making the choice to drive. It is important for drivers to take prescription medications as prescribed and use caution before putting themselves and others at risk on the road..

Zero tolerance drug laws need to legally protect citizens from unwarranted and unreasonable prosecution when they legally consume prescription drugs as directed by a prescribing health care professional.

By providing that a person may raise an “affirmative defense” when they have cooperated in being tested and they have a prescription that they have consumed in conformity with the health care provider’s orders, states with zero tolerance drug laws can provide due process of law to protect citizens’ rights.

Drivers who use prescription drugs illegally – that is without a valid prescription – are not provided an affirmative defense to the zero tolerance per se drug law because the drug use is illegal.

How was the 0.08 percent Blood Alcohol Concentration (BAC) limit for alcohol per se laws determined?

Today’s 0.08 percent BAC limit for alcohol was not scientifically determined; it was politically determined, with scientific help. Although it is illegal in the U.S. for any driver age 21 or older to drive with a BAC of 0.08 percent or higher, other countries use far lower limits. Many European countries use a 0.05 percent limit. Sweden uses 0.02 percent and Poland uses 0.03 percent. Yet, the science on which these numbers were based is the same.

Laboratory tests on human volunteers demonstrated that impairment could be seen at BAC levels as low as 0.02 percent. Impairment was very minimal at low doses and increased as the dosage was increased. Due to normal biological variability, the increase in impairment was not uniform with all subjects. Reviewers of the data in the U.S. determined that a dosage of 0.08 percent was a reasonable number to define for all adults an unsafe level of impairment. Reviewers in other countries settled on different numbers based on their cultural norms.

In the U.S., this means that for any driver, a 0.08 percent BAC is per se evidence of drunk driving. For many drivers a BAC of less than 0.08 percent is impairing. Likewise, some alcohol-tolerant drivers may not demonstrate the same level of impairment at 0.8 percent BAC. This means that a DUI suspect who has a BAC of 0.07 percent would not be guilty under an alcohol per se law; however, that driver and any DUI suspect with less than 0.08 percent BAC can be prosecuted under the impairment prong of the law where evidence must be provided to demonstrate impairment. The 0.07 percent BAC alone is not sufficient evidence to prove impairment.

Some opponents of per se drugged driving laws cite the lack of scientific consensus of drugs’ dose/impairment relationship as sufficient reason not to adopt drug per se laws. However, as discussed here, even though scientific consensus exists for alcohol impairment as it does for drug impairment, the politics and policies may differ from one jurisdiction to another.

What specimens are used for drug testing?

In some states, blood or urine may be used to detect drugs among impaired driving suspects; however, oral fluid provides a viable and reliable testing option. Oral fluid testing is a non-invasive method of sample collection and eliminates gender requirements. Oral fluid testing identifies recent drug use and the parent drug as well. Oral fluid testing decreases the potential use of adulterants or specimen tampering and can detect drugs within minutes. It is being used in numerous other countries but outside of a few states that are conducting oral fluid projects with local law enforcement and District Attorneys, it is not accepted here as a viable testing method at this time. Currently, only 14 States allow for oral fluid testing.


  1. Julianna says:

    That said, insurance companies don’t all think the same way about driving while intoxicated, nor do they treat all DWI convictions equally. In other words, if your driving record was spotless before your conviction, and it was your first offense, then your premium payments may be only slightly higher than before.

  2. […] it is legal to drive in Florida with illegal drugs in a driver’s system. Most states have passed a “0 per se law,” which is a zero tolerance per […]

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