Alcohol, Drugs and Pilots
FAA Alcohol & Drug Rules for Pilots
A pilot may not attempt to fly an aircraft or even attempt to be a crew member of a civil aircraft 1:
Passengers & Crew Members
A pilot of a civil aircraft may not even allow a person to board an aircraft as a passenger or otherwise if that person appears to be intoxicated or appears to be under the influence of drugs. The law provides an exception in case of an emergency: TITLE 14--AERONAUTICS AND SPACE CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 91 GENERAL OPERATING AND FLIGHT RULES Subpart A, Sec. 91.17 Alcohol or Drugs (b) Except in an emergency, no pilot of a civil aircraft may allow a person who appears to be intoxicated or who demonstrates by manner or physical indications that the individual is under the influence of drugs (except a medical patient under proper care) to be carried in that aircraft.1
It seems hard to imagine an emergency that would allow a pilot to permit someone under the influence of alcohol or drugs to board the aircraft as a passenger.
It's not easy being a pilot. See this police Complaint/Arrest Affidavit about two passengers who were arrested for assaulting a pilot who escorted them off the aircraft because they appear to be either intoxicated or on narcotic drugs.