Dangerous / Vicious Dogs

If you are approached by a dog(s) and you think the dog(s) act in a behavior that may cause a threat to yourself or others, please contact Animal Control or your local police department. Animal Control is responsible by state law to investigate any complaint regarding dogs that may pose a threat to yourself or others.
The following are excerpts from the Illinois Animal Control Act:
(510 ILCS 5/2.05a)
    Sec. 2.05a. "Dangerous dog" means (i) any individual dog anywhere other than upon the property of the owner or custodian of the dog and unmuzzled, unleashed, or unattended by its owner or custodian that behaves in a manner that a reasonable person would believe poses a serious and unjustified imminent threat of serious physical injury or death to a person or a companion animal or (ii) a dog that, without justification, bites a person and does not cause serious physical injury.   
(510 ILCS 5/2.19b)
    Sec. 2.19b. "Vicious dog" means a dog that, without justification, attacks a person and causes serious physical injury or death or any individual dog that has been found to be a "dangerous dog" upon 3 separate occasions.
 (510 ILCS 5/2.18a)
    Sec. 2.18a. "Physical injury" means the impairment of physical condition.
(510 ILCS 5/2.19a)
    Sec. 2.19a. "Serious physical injury" means a physical injury that creates a substantial risk of death or that causes death, serious disfigurement, protracted impairment of health, impairment of the function of any bodily organ, or plastic surgery.
(510 ILCS 5/2.16) (from Ch. 8, par. 352.16)
    Sec. 2.16. "Owner" means any person having a right of property in an animal, or who keeps or harbors an animal, or who has it in his care, or acts as its custodian, or who knowingly permits a dog to remain on any premises occupied by him or her. "Owner" does not include a feral cat caretaker participating in a trap, spay/neuter, return or release program.
  (510 ILCS 5/16) (from Ch. 8, par. 366)
    Sec. 16. Animal attacks or injuries. If a dog or other animal, without provocation, attacks, attempts to attack, or injures any person who is peaceably conducting himself or herself in any place where he or she may lawfully be, the owner of such dog or other animal is liable in civil damages to such person for the full amount of the injury proximately caused thereby.