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Driving Under the Influence of Drugs

New Jersey enacted the nation's first driving under the influence (DUI) law in 1906. However, it wasn't until the 1970s and 1980s that awareness about the seriousness of driving while impaired began to gain attention. For the most part, these early DUI laws focused on alcohol intoxication. Yet many substances can impair your ability to operate a motor vehicle. Intoxicating substances may include over-the-counter and prescription medications as well as illegal drugs.

As addiction and substance abuse rates continue to rise, so does driving under the influence of drugs. A 2021 Substance Abuse and Mental Health Services Administration (SAMHSA) survey found that roughly 11.7 million Americans drove under the influence of drugs in the previous year. More than 54% of people involved in fatal crashes or injuries tested positive for at least one illicit or prescription medication in 2021, according to a study by the National Highway Traffic Safety Administration (NHTSA).

Evidence suggests an increased crash risk for drug-impaired driving compared to alcohol-impaired driving. Driving under the influence of any intoxicating substance can lead to a DUI charge.

Drug-Impaired Driving

It is illegal in all states to operate a motor vehicle while under the influence of an intoxicant. The process is the same regardless of whether you have been drinking alcohol, have consumed drugs, or both. When a police officer suspects you of driving while intoxicated (DWI), they will ask you to perform field sobriety tests and submit to chemical tests. Field sobriety tests gauge your intoxication but also look for signs of being under the influence of controlled substances. Chemical tests will measure the amount of alcohol in your system and other substances consumed.

Every state has implied consent laws that expect you to cooperate with these tests. You agreed to obey the law when you obtained your driver's license. Part of the law is participating in chemical tests when a law enforcement officer believes they are necessary.

You can refuse chemical tests but may face immediate license suspension and other penalties. Also, law enforcement can still arrest you. Officers will likely submit evidence of your refusal to the court.

All 50 states have drug recognition experts (DREs). DREs are specially trained and certified law enforcement officers who follow specific guidelines to determine drug impairment in motorists. DREs closely examine a person's eye movements, behavior, and other cues pointing to drug use.

Most DUI cases — particularly for a first offense — are misdemeanors unless certain aggravating factors exist. These factors include having a minor in your vehicle, having an excessively high blood alcohol concentration, or causing an accident with bodily injury.

You can face additional criminal charges if you possess illegal substances when you're arrested. You may also face charges for possession of an illegal or controlled substance in addition to a DUI.

Measuring Drug Impairment

There are no universally accepted limits for the drug amount in your system. DUI laws have set a blood alcohol content (BAC) legal limit. You are too impaired to be driving at or above this limit. There is no similar measure for drug intoxication.

Alcohol passes through the body rapidly. Measuring a motorist's BAC during a traffic stop is also easy. Breathalyzer or breath tests are considered accurate under the law and are usually confirmed with a blood or urine test.

Most drugs do not get flushed from your body as quickly as alcohol. For example, the psychoactive component of cannabis, delta-9-tetrahydrocannabinol (THC), is usually detectable in your urine or bloodstream for up to seven days, though sometimes it can take weeks or months to leave your system. Testing can find THC in your hair up to 90 days after use. Cocaine, on the other hand, typically leaves the body after three days.

The majority of states have impairment-based DUI laws. Under these statutes, there must be proof of impaired driving. A positive drug test counts, but evidence can also include a failed field sobriety test, testimony about your behavior during the traffic stop, and reckless driving.

A urinalysis, blood sample, and saliva testing look for the presence of drugs. A few states have established pilot programs for the roadside testing of oral fluids. These tests should determine the presence of THC, methamphetamines, and opioids.

Legal and Decriminalized Cannabis

One of the most common drugs involved in DUIs is cannabis. More states have moved to legalize or decriminalize cannabis. However, legally being able to access cannabis or having a prescription to use marijuana does not make it legal to drive after consuming it.

Motorists who live in states that permit medical use of cannabis with a valid doctor's recommendation may still get a DUI. If a police officer or DRE has gathered enough evidence of cannabis or marijuana impairment, a prescription may not be a criminal defense. In this regard, medical cannabis is no different from other prescription drugs with the potential for impairment.

Drugged Driving Per Se Laws

At least five states have per se drugged driving laws. Much like alcohol per se laws, these DUI laws make it illegal to operate a motor vehicle with a specific amount of THC or its metabolite in your system. Depending on your state, this amount can vary from 2 nanograms (ng) of THC per milliliter (ml) of blood to 5 ng/ml.

You are impaired under the law if you have more than the legal amount in your system. Law enforcement officers can arrest you. The prosecution doesn't need more evidence of your intoxication and doesn't need to prove impairment. A valid, positive test is enough.

Colorado's law does not rise to the level of a per se law but is similar. Under Colorado's permissible inference law, law enforcement can assume intoxication if you have 5 ng/ml of THC in your system. However, you can argue in court that you are not impaired at this level.

At least three states — NevadaOhio, and Virginia — have per se laws that apply to other substances. These may include cocaine, opioids, and methamphetamines, depending on the state.

California has gone a step further in its drugged driving laws. It is illegal for certain known active drug addicts or chronic drug users to operate a motor vehicle. California reasons that the withdrawal symptoms associated with addiction make driving as dangerous as being under the influence.

Zero-Tolerance Laws

Illegal and controlled substances generally fall under a state's zero-tolerance laws. This means you are breaking the law by consuming any detectable amount of an illicit substance. Testing positive for controlled substances will result in a DUI charge.

At least 12 states have zero-tolerance laws that include the presence of THC, even if cannabis use is legal. Being under the influence of THC can reduce your ability to drive. It can slow your reaction time, make you feel drowsy, and distort your perception.

Drugged Driving Penalties

Penalties for a drug-based DUI conviction are generally the same as a drunk driving conviction. You will face heavy fines and revocation of your driver's license. You might serve jail time and probation. The judge can order you to perform community service hours. Some jurisdictions require you to take part in victim impact panels, which allow victims of DUI drivers to share their stories.

Most states will require you to undergo substance abuse education and treatment. Your state's department of motor vehicles (DMV) will have additional requirements for you to get your driver's license reinstated. One requirement may be installing an ignition interlock device (IID). An IID prevents your vehicle from starting if the breath-testing device attached to your ignition detects alcohol. These are mandatory in many jurisdictions, particularly if you have convictions for drugs or alcohol.

A DUI conviction stays on your record for years and will appear on most routine background checks. This may cost you future jobs and housing. It can even prevent you from getting financial aid for college. You will pay more for auto insurance.

Very few states allow expungement of a DUI conviction if you are over 21 years old.

Impairing Effects of Various Illegal Drugs

Different drugs affect drivers in different ways. But those that impair judgment, alertness, concentration, or motor skills may be as dangerous as — if not more than — alcohol.

  • Marijuana or cannabis: Relaxation, euphoria, disorientation, drowsiness, difficulty with coordination, slowed response, and increased heart rate
  • CocaineEuphoria, excitation, dizziness, increased focus and alertness, confusion and disoriented behavior, irritability, paranoia, aggressiveness, increased heart rate
  • Methamphetamine: Excitation, hallucinations, insomnia, poor impulse control, increased heart rate and blood pressure
  • Morphine and heroin: Intense euphoria, drowsiness, sedation, disconnectedness, mental clouding, analgesia, depressed heart rate, nausea and vomiting, diminished reflexes
  • Lysergic acid diethylamide (LSD): Hallucinations; altered mental state; delusions; impaired depth, time, and space perception; inability to think or communicate rationally

Prescription and Over-the-Counter Drugs

Some drugs purchased at a pharmacy, whether they're prescribed by a doctor or bought over-the-counter (OTC), can be as dangerous as alcohol and can trigger a DUI. Look for warning labels or ask your pharmacist if you doubt a drug's capacity for impairment.

Some standard prescription and OTC drugs that can impair drivers include:

  • Opioids: Includes fentanyl, codeine, oxycodone, and methadone. Drowsiness, euphoria, nausea, slowed breathing
  • Valium: 10 mg of this tranquilizer can cause impairment similar to a 0.10% BAC
  • Dextromethorphan: Cough medicine may cause euphoria, slurred speech, dizziness, drowsiness, nausea, and vomiting
  • Antihistamines: Slowed reaction time, impaired coordination, drowsiness
  • Decongestants: Drowsiness, anxiety, and dizziness
  • Sleeping pills: Even the next morning, the residual effects of these drugs can impair drivers

Arrested for Driving Under the Influence of Drugs? Get Legal Help

A DUI charge and conviction can have serious and long-term consequences. You can face jail time, significant fines, and loss of your driver's license. If you're facing a charge of driving under the influence of alcohol or drugs, contacting a skilled DUI attorney near you is in your best interest. A DUI defense attorney can advise you of your options and fight for the best outcome.

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