In order to make an arrest for driving under the influence, Portland police must have evidence that the person is intoxicated. To gather this evidence, police will often perform one or more blood alcohol content level tests. These tests can include breath tests, blood tests or field sobriety tests. Unlike breath tests or blood tests, a field sobriety test cannot read the exact amount of alcohol in a person's blood. Instead, the test measures certain behaviors and reactions that can suggest that a person has been drinking.
When people are questioned by police following a traffic stop, they may want to refuse to submit to a field sobriety test. Nonetheless, under Oregon code section 813.135, refusing a field sobriety test is not allowed. According to that statute, any driver on Oregon's roads has given implied consent to submit to the test. This rule applies to anyone operating a vehicle on the state's highways or on any road open to the public.