Driving High vs Driving Drunk

With 24 states now legalizing recreational cannabis use, questions are rising about how marijuana may impact driving safety and contribute to impaired driving incidents. In fact, many cannabis users believe driving after using marijuana is less dangerous than driving after drinking alcohol. 

Other drug users may also drive high, putting themselves and others at risk. So, is driving high really that dangerous? What are the legal implications? How does driving drunk or high impact your ability to drive? In this article, we take a closer look, ensuring you follow the rules of the road.

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What Is Considered “Driving High” or “Driving Drunk”?

Legal definitions of impaired driving vary by state, but they generally focus on measurable impairment rather than subjective feelings¹. Driving drunk typically means operating a vehicle with a blood alcohol concentration (BAC) of 0.08% or higher—a standard in all 50 states². This objective measurement provides a clear threshold for law enforcement.

Driving high, unfortunately, lacks such precision. Unlike alcohol, THC (the psychoactive component in cannabis) doesn’t correlate consistently with impairment levels³. Some states have zero-tolerance policies for any detectable THC. Yet, others specify limits ranging from two to five nanograms per milliliter of blood⁴ - thresholds many experts consider arbitrary.

The challenge lies in how cannabis remains detectable for days or weeks after use, long after impairment has subsided. This creates complications for both law enforcement and cannabis users trying to follow the law responsibly. So, let’s take a closer look at how alcohol versus cannabis affects driving ability exactly.

How Alcohol Affects Driving Ability

Alcohol impairs driving in predictable, dose-dependent ways that researchers have documented extensively. Even at low levels, alcohol begins degrading coordination, judgment, and reaction time—skills crucial for safe driving.

At a BAC of 0.05%, drivers typically experience reduced coordination, difficulty tracking moving objects, and decreased response to emergency situations⁵. By 0.08%, these effects worsen substantially, with impaired concentration, short-term memory, speed control, and information processing⁶.

Perhaps most dangerously, alcohol creates a disconnect between impairment and self-awareness. The more intoxicated a person becomes, the less capable they are of recognizing their impairment, often leading to overconfidence and riskier driving behaviors.

How Cannabis Affects Driving Ability

While alcohol typically produces a predictable dose-response relationship, the effects of THC—the active compound in cannabis—are more variable. Impairment depends on several factors, including dosage, method of consumption, individual tolerance, and whether it's used alongside other substances. Combining cannabis with alcohol, for example, significantly worsens impairment⁷.

THC can impair critical driving-related skills such as attention, concentration, reaction time, and perception of time and speed. These effects are especially problematic during tasks that require divided attention or quick decision-making.

‍Studies using driving simulators have shown that cannabis users often drive more slowly, maintain longer following distances, and take fewer risks compared to those impaired by alcohol. However, this compensatory behavior does not fully offset impairment. 

Cannabis users still show reduced performance in complex situations, including difficulty maintaining proper lane position, especially on winding or unfamiliar roads. Reaction times are slower, and multitasking - such as navigating while responding to sudden changes - becomes significantly more difficult.

While some users may feel more cautious under the influence of cannabis, the decline in coordination, attention, and decision-making can still pose serious risks on the road.

How Other Drugs Affect Driving Ability

Beyond alcohol and cannabis, numerous substances - both legal and illegal - can significantly impair driving ability, often in ways that aren't immediately obvious to the user.

For example, prescription medications, even when taken as directed, frequently cause driving impairment⁸. Opioid painkillers slow reaction time and can induce drowsiness similar to alcohol. Benzodiazepines like Xanax or Valium impair coordination and cognitive function, with effects sometimes lasting into the following day after use.

While substances like cocaine or methamphetamine initially increase alertness, they also promote aggression, impulsivity, and risky driving behaviors. As the drugs wear off, extreme fatigue can suddenly overcome users, creating dangerous situations on the road.

Hallucinogens and dissociatives, including LSD and PCP, drastically alter perception of reality and spatial awareness, making safe driving impossible. Even common over-the-counter medications containing diphenhydramine (Benadryl) can cause significant drowsiness and slowed reaction time.

Additionally, polysubstance use - combining multiple drugs or mixing drugs with alcohol - creates unpredictable and often dramatically amplified impairment. These combinations frequently appear in fatal crash toxicology reports, underscoring their particular danger.

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Legal Consequences of DUI

Driving under the influence carries severe legal penalties that can impact your life for years. First-time offenders typically face fines ranging from $500 to $2,000, license suspension for three to 12 months, and possible jail time of up to six months⁹. 

Subsequent offenses escalate dramatically, with some states imposing felony charges, mandatory imprisonment, and permanent license revocation for third offenses. 

Beyond the criminal consequences, a DUI often triggers insurance rate increases of 80% or more, mandatory installation of ignition interlock devices, and potential professional ramifications, including job loss or licensing issues. Even years later, a DUI conviction can complicate housing applications, employment opportunities, and international travel.

Put simply, it’s not worth it. But for those struggling with an addiction, it can sometimes feel like a necessary part of life. However, there’s hope. Recovery is possible. At Freedom Recovery Centers (FRC), our team is here to support you every step of the way. Don’t wait another day to get the help you need and deserve. Call us at 804-635-3746 or fill out our online form.