(1) For the purposes of ORS 161.233 and 161.242, a reasonable belief that a person has committed an offense means a reasonable belief in facts or circumstances which, if true, would constitute an offense.
(2) A peace officer who is making an arrest is justified in using the physical force prescribed in ORS 161.233 and 161.242 unless the arrest is unlawful and is known by the officer to be unlawful.