§ 132.21  DETENTION; AFFIRMATIVE DEFENSE.
   (A)   Detention. Any merchant who has reasonable grounds to believe that a person has committed retail theft may detain the person, on or off the premises of a retail mercantile establishment, in a reasonable manner and for a reasonable length of time for all or any of the following purposes:
      (1)   To request identification;
      (2)   To verify such identification;
      (3)   To make reasonable inquiry as to whether such person has in his possession  unpurchased merchandise and to make reasonable investigation of the ownership of such merchandise;
      (4)   To inform a peace officer of the detention of the person and surrender that person to the custody of a peace officer;
      (5)   In the case of a minor, to immediately make a reasonable attempt to inform the parents, guardian or other private person interested in the welfare of that minor and, at the merchant's discretion, a peace officer, of this detention and to surrender custody of such minor to such person.
   A merchant may make a detention as permitted in this section off the premises of a retail mercantile establishment only if such detention is pursuant to an immediate pursuit of such person.
   A merchant shall be deemed to have reasonable grounds to make a detention for the purposes of this section if the merchant detains a person because such person has in his or her possession either a theft detection shielding device or a theft detection device remover.
   (B)   Affirmative defense. A detention as permitted in this section does not constitute an arrest or an unlawful restraint, as defined in ILCS Ch. 720, Act 5, § 10-3, nor shall it render the merchant liable to the person so detained.
   (C)   For the purposes of this section, MINOR  means a person who is less than 19 years of age, is unemancipated, and resides with his or her parent or parents or legal guardian.
(ILCS Ch. 720, Act 5, § 16-26)