What does "zero tolerance" actually mean if you had just one drink? It means the law sets an extremely low limit and gives officers very little room to overlook alcohol or drugs in certain situations. Most often, zero tolerance laws apply to underage drivers, commercial drivers, or drivers under special restrictions. For under-21 drivers, even a small amount of alcohol that would be below the standard adult BAC limit can still trigger a violation, license penalties, and a DUI-related case.

In Hawaii, the big one is Hawaii Revised Statutes §291E-64, which bars drivers under 21 from operating a vehicle with a blood alcohol concentration of 0.02% or more after consuming alcohol. That is far below the usual 0.08% adult DUI threshold. So if a young driver is stopped after a crash, "I wasn't drunk" is not much of a defense if the test result crosses that lower line.

Practically, the move is simple: do not drive at all after drinking if you are under 21 or subject to a restricted license. In an injury case, a zero tolerance violation can become strong evidence of negligence and bad decision-making. Hawaii also uses modified comparative fault with a 51% bar, so blame matters. If the underage driver's violation helped cause the wreck, that can seriously affect who pays damages and how much can be recovered.