Ok, this is somewhat of a trick question. Most of us are familiar with, or have at least heard of, roadblocks in which police will be stop vehicles to do sobriety checks. While many jurisdictions allow such stops, Oregon does not.
The Oregon Supreme Court expressly has stated Article 1, Section 9 of the Oregon Constitution (dealing with unreasonable searches and seizures) prohibits such police actions. There have been many attempts to legalize such roadblocks, but as of yet, such attempts have been unsuccessful. So, for now, in the State of Oregon, you should not run in to an issue of roadblock checkpoints for driving under the influence.