(A)   No person shall knowingly resist or obstruct the performance by one known to the person to be a peace officer, firefighter or correctional institution employee of any authorized act within his or her official capacity.
   (B)   For the purpose of this section, the following definitions shall apply unless the context clearly indicates or requires a different meaning.
      CORRECTIONAL INSTITUTION EMPLOYEE. Any person employed to supervise and control inmates incarcerated in a penitentiary, state farm, reformatory, prison, jail, house of correction, police detention area, half-way house or other institution or place for the incarceration or custody of persons under sentence for offenses or awaiting trial or sentence for offenses, under arrest for an offense, a violation of probation, a violation of parole, a violation of aftercare release, a violation of mandatory supervised release, or awaiting a bail setting hearing or preliminary hearing, or who are sexually dangerous persons or who are sexually violent persons.
      FIREFIGHTER. Any individual, either as an employee or volunteer, of a regularly constituted fire department of a municipality or fire protection district who performs firefighting duties, including, but not limited to, the Fire Chief, Assistant Fire Chief, Captain, engineer, driver, ladder person, hose person, pipe person and any other member of a regularly constituted fire department. FIREFIGHTER also means a person employed by the office of the State Fire Marshal to conduct arson investigations.
   (C)   It is an affirmative defense to a violation of this section if a person resists or obstructs the performance of one known by the person to be a firefighter by returning to or remaining in a dwelling, residence, building or other structure to rescue or to attempt to rescue any person.
(ILCS Ch. 720, Act 5, § 31-1)  (1999 Code, § 133.01)  Penalty, see § 130.99