ORS § 813.150
In addition to a chemical test of the breath, blood or urine administered under ORS 813.100 or 813.140, upon the request of a police officer, a person shall be permitted upon request, at the person's own expense, reasonable opportunity to have any licensed physician and surgeon, licensed professional nurse or qualified technician, chemist or other qualified person of the person's own choosing administer a chemical test or tests of the person's breath or blood for the purpose of determining the alcoholic content of the person's blood or a chemical test or tests of the person's blood or urine, or both, for the purpose of determining the presence of cannabis, psilocybin, a controlled substance or an inhalant in the person. The failure or inability to obtain such a test or tests by a person shall not preclude the admission of evidence relating to a test or tests taken upon the request of a police officer.
ORS 813.150