Oregon:ORS 811.410(1)(a)
- Unsafe passing on left; penalty.
- (1) A person commits the offense of unsafe passing on the left if the person violates any of the following requirements concerning the overtaking and passing of vehicles:
- (a) The driver of a vehicle that is overtaking any other vehicle proceeding in the same direction shall pass to the left of the other vehicle at a safe distance and shall not again drive to the right side of the roadway until safely clear of the overtaken vehicle.
(Source: http://www.leg.state.or.us/ors/811.html)