In Campbell v. Department of Licensing (1982) 31 Wn. App. 833 644 P.2d 1219, a passing motorist gave a Washington state trooper the description of a vehicle the motorist believed was being driven by a drunk driver. The trooper stopped the suspected drunk driver's vehicle even though the trooper had not observed any illegal activity or conduct indicative of drunk driving. (644 P.2d at p. 1220.) Upon investigation the trooper determined the driver was in fact under the influence of alcohol. (Ibid.) The Washington State Court of Appeals held that "in the absence of any corroborative information or observation, a police officer is not authorized to stop a vehicle on the sole basis that a passing motorist points to a vehicle and announces that it is being driven by a drunk driver." (Ibid.) The court concluded the trooper had "absolutely nothing to suggest that the driver was under the influence of intoxicating liquor except a conclusory tip from a unidentified passing motorist that the driver was drunk." (Id. at p. 1221.) The court pointed out that the passing motorist provided no factual information from which the trooper could assess the probable accuracy of the motorist's conclusion, plus the trooper saw nothing that would have corroborated the tip. (Ibid.)