Illinois Pattern Jury Instructions–Criminal (IPJI-Crim)
IL 24-25.16 Private Person’s Use Of Force In Making Arrest–Not Summoned By Peace Officer
A private person who [(makes) (assists another private person in making)] a lawful arrest need not retreat or desist from efforts to make a lawful arrest because of resistance or threatened resistance to the arrest. He is justified in the use of any force which he reasonably believes to be necessary to effect the arrest and of any force which he reasonably believes to be necessary to defend [(himself) (another)] from bodily harm while making the arrest.
[However, he is justified in using force likely to cause death or great bodily harm only when he reasonably believes that such force is necessary to prevent death or great bodily harm to [(himself) (another)].]