P was the operator of a vehicle that turned around before reaching a roadblock set up to detect persons operating motor vehicles while under the influence of alcohol. P was pursued and stopped, and subsequently arrested for operating under the influence. At trial, the District Court suppressed all evidence obtained following the stop on the ground that the arresting officer lacked a reasonable and articulable suspicion of criminal activity to justify the stop of P's vehicle. P's license to operate a motor vehicle was suspended by D based on the arresting officer's report, and the results of the blood-alcohol test administered to P. P invoked his right to a hearing on the administrative license suspension. P contested only the issue of probable cause and argued that the decision of the District Court to suppress all evidence flowing from the stop was binding on the administrative proceeding and that the exclusionary rule should apply. The examiner ruled that his only statutory task was to determine whether there was probable cause to believe that P was operating with excessive alcohol in his blood. After determining that neither the exclusionary rule nor principles of collateral estoppel applied to an administrative license suspension hearing, upheld P's suspension. Pl appealed. The Superior Court vacated the decision of the hearing examiner, concluding that because the administrative license suspension was 'quasi-criminal,' P was entitled to have the exclusionary rule applied, and to have the admissibility of evidence tested according to general notions of 'due process and fair play.' D appealed.