How Florida DUI standards apply to cannabis impairment

Florida doesn’t need a specific “THC limit” to arrest or prosecute a DUI involving marijuana. The legal backbone is Florida’s general DUI law, which treats alcohol and drugs under the same core standard: whether a driver’s “normal faculties” were impaired while driving (or in “actual physical control” of a vehicle).

The legal standard: “normal faculties” impairment (not a THC number)

Florida Statute § 316.193 makes it a DUI if a person is under the influence of alcoholic beverages, certain “chemical substances,” or any controlled substance under Chapter 893 “when affected to the extent that the person’s normal faculties are impaired.”

Florida Statute § 316.1934 expands what “normal faculties” means in practice: the ability to see, hear, walk, talk, judge distances, drive, make judgments, act in emergencies, and generally perform the mental and physical acts of daily life.

That’s why marijuana DUIs in Florida are typically built as impairment cases, not “per se” chemical-threshold cases (the way alcohol DUIs often are at 0.08 BAC).

“No per se marijuana limit”—what that means on the road

Florida’s own highway safety messaging states plainly that, unlike alcohol, there is no specific impairment limit with marijuana, and effects can vary widely person-to-person and last differently than alcohol.

In real traffic stops, that pushes the focus toward observations and behavior, such as:

• driving pattern (lane position, speed control, reaction to signals),
• the driver’s appearance and speech,
• attention and coordination,
• performance on roadside tasks.

How officers try to document cannabis impairment

Because there’s no Florida “legal THC number” that automatically proves impairment, officers often rely on Standardized Field Sobriety Tests (SFSTs) and, in some jurisdictions/cases, a Drug Recognition Expert (DRE) evaluation after arrest.

NHTSA describes the DRE/DEC process as a standardized, post-arrest procedure using observable signs, psychophysical tests, eye observations in different lighting, and vital signs to identify likely drug categories—often followed by blood or urine testing for laboratory analysis and corroboration.

Chemical testing: urine/blood requests and refusal consequences

Florida’s implied consent framework allows breath testing for alcohol and also authorizes urine testing (and sometimes blood, depending on circumstances) when an officer has reasonable cause to believe a person was driving under the influence of chemical or controlled substances.

A key practical point: THC can be detectable longer than the window of actual impairment, and different tests measure different compounds (active THC vs. metabolites). That’s one reason Florida impairment cases often lean heavily on totality of evidence—driving behavior + roadside observations + trained-evaluator findings + toxicology—rather than toxicology alone.

Medical marijuana doesn’t create a “DUI exception”

Even if cannabis is lawfully possessed or used under Florida’s medical program, the DUI question remains the same: were the driver’s normal faculties impaired while operating or controlling a vehicle? The statute is impairment-based, not permission-based.

This is general legal information, not legal advice. If you want, tell me whether you want the article framed for everyday drivers, medical patients, or dispensary education—and I’ll tailor the examples and “what to do if stopped” safety guidance accordingly.