John is a licensed barber in State A. The State A barber licensing statute provides that the Barber Licensing Board may revoke a barber license if it finds that a licensee has used his or her business premises for an illegal purpose. John was arrested by federal narcotics enforcement agents on a charge of selling cocaine in his barbershop in violation of federal laws. However, the local United States Attorney declined to prosecute and the charges were dropped. Nevertheless, the Barber Licensing Board commenced a proceeding against John to revoke his license on the ground that John used his business premises for illegal sales of cocaine. At a subsequent hearing before the board, the only evidence against John was affidavits by unnamed informants, who were not present or available for cross-examination. Their affidavits stated that they purchased cocaine from John in his barbershop. Based solely on this evidence, the board found that John used his business premises for an illegal purpose and ordered his license revoked. In a suit by John to have this revocation set aside, his best constitutional argument is that 
John's inability to cross-examine his accusers denied him a fair hearing and caused him to be deprived of his barber license without due process of law. the administrative license revocation proceeding was invalid, because it denied full faith and credit to the dismissal of the criminal charges by the United States Attorney.  Article III requires a penalty of the kind imposed on John to be imposed by a court rather than an administrative agency. the existence of federal laws penalizing the illegal sale of cocaine preempts state action relating to drug trafficking of the kind involved in John's case.