Oregon Revised Statutes Crimes and Punishments § 161.215

(1) With intent to cause physical injury or death to another person, the person provokes the use of unlawful physical force by that person; or

(2) The person is the initial aggressor, except that the use of physical force upon another person under such circumstances is justifiable if the person withdraws from the encounter and effectively communicates to the other person the intent to do so, but the latter nevertheless continues or threatens to continue the use of unlawful physical force; or

(3) The physical force involved is the product of a combat by agreement not specifically authorized by law.