ORS § 311.232
If any officer described in ORS 311.216 to 311.232 fails to comply with ORS 311.216 to 311.232 on the discovery by the officer, or on credible information being furnished by another person, that property has been omitted from taxation, the state, on the relation of any state officer or of any taxpayer of the county in which the failure occurs, may proceed against the officer in any court of competent jurisdiction by mandamus to compel the officer to comply with ORS 311.216 to 311.232. In the trial of the suit the question of what constitutes credible information is a question of fact to be determined by the court trying the case in the same manner other issues of fact are determined. If judgment is rendered that credible information has been discovered by or furnished to the officer, or that the officer has reason to believe that property has been omitted from taxation, the officer shall forthwith place the omitted property on the assessment and tax roll in accordance with ORS 311.216 to 311.232. If judgment is rendered against the officer, the officer shall be liable for all costs of the mandamus suit, and for a reasonable attorney fee at trial and on appeal for relator's attorney, which shall be taxed as a part of the costs of the suit. If proceedings are instituted under this section on the relation of any private individual, the relator shall give bond to the satisfaction of the court to pay all costs that may be recovered against the relator.
ORS 311.232