The decision in Gerstein v. Pugh clearly established this principle and formed the basis for similar analyses in Federal court decisions in Fisher v. Washington Metropolitan Area Transit Authority and Sanders v. City of Houston. These decisions rested on the reasonableness standard of the fourth amendment and asserted that an officer's ad hoc assessment of probable cause permits brief custodial detention to permit law enforcement officers to take the necessary administrative steps which are related to arrest. This analysis balances the recognition of individual liberty with the Supreme Court's reluctance to extend adversary safeguards to probable cause hearings. These safeguards would be required under a due process analysis based on the 14th amendment, which was considered in the case of Patzig v. O'Neil. Imposing due process guarantees on probable cause hearings would cause longer periods of postarrest detention and would work against the prohibition against postarrest, prehearing detention of unreasonable duration. Federal courts are likely to hear an increased number of actions based on this issue as more practitioners become aware of the limitations imposed by the fourth amendment. A total of 111 footnotes are provided.