Believe it or not, this is not that stupid question. And believe it or not, the answer is, technically, yes.
California’s Vehicle Code section 23152(b), like all states, prohibits driving a vehicle with a blood alcohol content of 0.08 percent or more in the system. Obviously caffeine alone will not give a person a blood alcohol level. Therefore, a person who only ingested caffeine will likely not be charged with California Vehicle Code section 23152(b).
However, under California Vehicle Code section 23152(a), a person can be charged with a DUI if they drive “under the influence” of alcohol and/or drugs. It does not matter if the drugs that caused a driver to be “under the influence” are illegal drugs, prescription drugs, or even over the counter drugs like caffeine.
Under California’s jury instruction, CALJIC 16.831, if a person ingests caffeine and, as a result, “their physical or mental abilities are impaired to such a degree that they no longer have the ability to drive a vehicle with the caution characteristic of a sober person of ordinary prudence under the same or similar circumstances,” they can be charged with a California DUI.
While caffeine can provide a temporary alertness to some, to others, especially those who are not used to consuming caffeine, it can also cause high blood pressure, anger and frustration, jitteriness, tremors, agitation, confusion, dehydration, and, in some cases, hallucinations. And, as improbable as it might seem, a person could technically fall under California’s definition of “under the influence” while on caffeine.