Division 1 of the Washington Court of Appeals concluded that once an officer forms a reasonable suspicion that a driver is under the influence, a DUI suspect has no 4th Amendment right to refuse tests that reveal whether the person is under the influence. Because the Standardized Field Sobriety Tests (SFSTs) are valided for precisely that purpose and are not overly intrusive or time consuming, the court concluded the request was reasonable and the refusal to peform those tests was indicative of consciousness of guilt and admissible for that purpose. While Washington courts had previously held that the refusal to perform SFSTs was admissible, that challenge was under the federal 5th Amendment.
The full case is available here: State v. Mecham (April 21, 2014)