38 U.S.C. § 105 : US Code - Section 105: Line of duty and misconduct

      (a) An injury or disease incurred during active military, naval,
    or air service will be deemed to have been incurred in line of duty
    and not the result of the veteran's own misconduct when the person
    on whose account benefits are claimed was, at the time the injury
    was suffered or disease contracted, in active military, naval, or
    air service, whether on active duty or on authorized leave, unless
    such injury or disease was a result of the person's own willful
    misconduct or abuse of alcohol or drugs. Venereal disease shall not
    be presumed to be due to willful misconduct if the person in
    service complies with the regulations of the appropriate service
    department requiring the person to report and receive treatment for
    such disease.
      (b) The requirement for line of duty will not be met if it
    appears that at the time the injury was suffered or disease
    contracted the person on whose account benefits are claimed (1) was
    avoiding duty by deserting the service or by absenting himself or
    herself without leave materially interfering with the performance
    of military duties; (2) was confined under sentence of court-
    martial involving an unremitted dishonorable discharge; or (3) was
    confined under sentence of a civil court for a felony (as
    determined under the laws of the jurisdiction where the person was
    convicted by such court).
      (c) For the purposes of any provision relating to the extension
    of a delimiting period under any education-benefit or
    rehabilitation program administered by the Secretary, the disabling
    effects of chronic alcoholism shall not be considered to be the
    result of willful misconduct.