Cannabis and driving laws

A law that permits a person to possess or use a substance is different from a law that defines impaired driving, and the two do different jobs. The driving offense is defined in a state's own vehicle or criminal code. That definition controls what is prohibited behind the wheel, whatever another body of law allows elsewhere.

The statutes quoted as examples below do not use the word cannabis. They rely on broader language. Arizona's statute refers to "any drug," North Carolina's to "an impairing substance," and Virginia's to "any narcotic drug or any other self-administered intoxicant or drug of whatsoever nature." Whether a specific substance falls within those terms depends on definitions outside the excerpts cited here. That question belongs with a lawyer in the state involved.

Because DUI is state law, the examples describe only what particular statutes say. They are not a national rule, and they do not describe what any state not named here provides.

A driver's license can be affected through a process that is separate from a criminal charge. Pennsylvania's Department of Transportation describes its process in its Driver's Manual guidance. That is agency guidance, not a statute.

According to the guidance, when a driving privilege is going to be suspended, revoked or disqualified, the Department mails a written notice listing the date the sanction will begin. The sanction starts on that effective date regardless of when the license or acknowledgment form is surrendered, and surrendering early does not start it early. By law, a license or acknowledgment form must be surrendered.

The guidance says the sanction may be appealed in the Court of Common Pleas (Civil Division) in the driver's county of residence. The appeal must be filed within a period measured from the mailing date of the Department's notice. In addition to serving the sanction, all restoration requirements must be satisfied before the privilege is restored. The guidance addresses licensing sanctions in general and does not single out drug-related cases. A Pennsylvania lawyer can explain how the notice and appeal provisions apply to a particular sanction.

Ohio Rev. Code § 4510.038 lists conditions that must be met before certain people may keep a license or have driving privileges reinstated. It applies to a person whose license is suspended, or who is granted limited driving privileges, under the provisions that section names. Each of these must occur:

- The person completes a remedial driving course approved by the director of public safety. - The registrar of motor vehicles examines the person and finds the person qualified to operate a motor vehicle. - The person gives and maintains proof of financial responsibility.

The statute requires the course to include instruction on alcohol, drugs and the operation of vehicles. That instruction includes a review of the laws on operating a vehicle under the influence of alcohol, drugs or a combination of them.

Ohio Rev. Code § 4506.23 is narrower. It concerns commercial driver's licenses and a specific commercial-driver violation that the section cross-references. It covers a person who refuses a test after the required warning, or whose test discloses either the presence of a controlled substance or an alcohol concentration at or above levels the statute sets. In those cases, the peace officer shall require the person to immediately surrender the commercial driver's license.

Arizona's statute, A.R.S. § 28-1381, makes it unlawful to drive or be in actual physical control of a vehicle in Arizona while under the influence of intoxicating liquor, any drug, a vapor releasing substance containing a toxic substance, or any combination of them, "if the person is impaired to the slightest degree."

Virginia's statute, Va. Code § 18.2-266, makes it unlawful to drive or operate a motor vehicle, engine or train while under the influence of any narcotic drug, other self-administered intoxicant or drug, or combination of such drugs, "to a degree which impairs his ability to drive or operate any motor vehicle, engine or train safely." It separately covers the combined influence of alcohol and drugs to that degree. It also provides that a charge under the section supports a conviction under any of its alternatives. For that article, "motor vehicle" includes mopeds while operated on Virginia's public highways.

North Carolina's statute, N.C. Gen. Stat. § 20-138.1, defines impaired driving as driving any vehicle on a highway, street or public vehicular area in North Carolina "while under the influence of an impairing substance." A related statute, N.C. Gen. Stat. § 20-12.1, applies the same language to a person serving as a supervising driver or approved instructor under the provisions it names. It makes that conduct an implied-consent offense.

Arizona's and North Carolina's statutes also contain provisions based on whether a drug is present, not only on impairment. A.R.S. § 28-1381 makes it unlawful to drive or be in actual physical control of a vehicle while the person's body contains any drug defined in a cross-referenced section of Arizona law, or that drug's metabolite. The text of that provision does not use the impairment language of the provision before it.

The same Arizona statute contains a prescription exception to that drug-presence provision. A person using a drug as prescribed by a medical practitioner who is licensed under the Arizona title the statute names, and who is authorized to prescribe the drug, is not guilty of violating it.

N.C. Gen. Stat. § 20-138.1 covers driving with "any amount" of a controlled substance in the person's blood or urine, or its metabolites, when that substance is on a schedule listed in a cross-referenced North Carolina statute.

Virginia's statute takes a different approach for a short list of named substances: cocaine, methamphetamine, phencyclidine and another substance identified by its chemical name. Each is covered at or above a blood concentration the statute sets. The excerpts do not answer whether a given substance falls within Arizona's or North Carolina's cross-referenced definitions.

In the statutes quoted as examples, the text says it is not, for the charges each provision covers.

Arizona's statute states that legal entitlement to use the drug under Arizona law is not a defense to a charge under its impairment provision. That statement is tied to the impairment provision only. Arizona's prescription exception, described above, applies to the drug-presence provision. These provisions sit in the same statute and keep their separate scopes.

North Carolina's statute states that the fact a person charged "is or has been legally entitled to use alcohol or a drug is not a defense to a charge under this section." It separately preserves a person's ability to argue that a chemical analysis result is inadmissible under a cross-referenced provision.

Texas's statute, Tex. Penal Code § 49.10, covers prosecutions under the intoxication offenses it lists. In those cases, being entitled to use the alcohol, controlled substance, drug, dangerous drug or other substance is not a defense.

None of these excerpts says how a particular card, certificate or prescription applies to a particular person. A lawyer in the relevant state can address that question.

Texas's implied-consent statute is Tex. Transp. Code § 724.011. It applies to a person arrested for an offense arising out of acts allegedly committed while operating a motor vehicle in a public place, or a watercraft, while intoxicated. It also applies to an arrest for an offense under a cross-referenced Alcoholic Beverage Code section. Subject to the chapter, that person is deemed to have consented to breath or blood specimens to determine alcohol concentration or the presence of a controlled substance, drug, dangerous drug or other substance.

Under Tex. Transp. Code § 724.063, evidence of such a substance, obtained by an analysis the chapter authorizes, is admissible in a civil or criminal action. Under Tex. Transp. Code § 724.018, a person who gave a specimen at a peace officer's request can ask for full information about the analysis. That information must be made available to the person or the person's attorney.

In Arizona, A.R.S. § 28-1388 covers blood drawn under a section it cross-references. Only a physician, a registered nurse or another qualified person may withdraw that blood to determine alcohol concentration or drug content. The statute also says the person tested shall be given a reasonable opportunity to arrange an additional test by a qualified person of their own choosing.

N.C. Gen. Stat. § 20-138.1 classifies impaired driving as a misdemeanor. Upon conviction, it directs the presiding judge to hold a sentencing hearing and impose punishment under a cross-referenced sentencing statute.

Under N.C. Gen. Stat. § 20-179.1, the trial judge may request a presentence investigation after a conviction for an offense involving impaired driving. The investigation looks at whether the person would benefit from treatment for habitual use of alcohol or drugs. If the person objects, no investigation may be ordered. The judge still keeps the power to order suitable treatment as a condition of probation, and must do so when a statute requires it.

In Arizona, A.R.S. § 28-1381 classifies a violation as a misdemeanor. At the arraignment, the court must tell the defendant that a jury trial may be requested and that the request, if made, shall be granted.

A lawyer licensed in the state involved can address questions such as these:

• Which provision of the state's statute is charged, and does it turn on impairment or on the presence of a substance?
• Does the state's definition of a drug or controlled substance cover the substance at issue?
• How does any prescription or other authorization relate to the charged provision, given the statute's wording?
• What license action is pending, in what forum, and by when must any request or appeal be filed?
• How was any blood or breath specimen collected and analyzed, and what information about the analysis can be obtained?

Deadlines, limits and penalty ranges are set by each state’s statutes, so this page does not state them. Each state page shows them with the official source and the date they were verified — or says plainly that a figure has not been confirmed yet.