Flying while drunk and related laws

Federal Air Regulation 91.17 (14 CFR 91.17) prohibits pilots from flying aircraft with an alcohol level of 0.04% or more, and/or within eight hours of consuming alcohol, and/or while under the impairing influence of any drug. The same prohibition applies to any other crewmembers on duty aboard the aircraft (flight attendants, etc.). Some airlines impose additional restrictions, and many pilots also impose stricter standards upon themselves. Commercial pilots found to be in violation of regulations are typically fired or resign voluntarily, and they may lose their pilot certificates and/or be subject to criminal prosecution under Federal or State laws, effectively ending their careers.
Similar laws apply to other activities involving transportation; Michigan prohibits intoxicated bicycling, horseback riding, buggy driving, use of motorized farm implements, or boating, the latter whether a pilot or passenger, with much the same threshold of intoxication.