Probable Cause: A Case Study

Police officers are faced with difficult decisions everyday. Is a warrant needed to make an arrest or to seize evidence or is there “probable cause” to proceed without a warrant?

Take the case of a narcotics agent who regularly gets information from a reliable informant. The information the informant has given the agent in the past has led to several arrests and convictions. One day, the informant tells the agent about a man, whom the agent has never met, who has gone to another city to purchase twenty kilograms of cocaine. Based on the tip, the agent goes to the airport, recognizes the man from the informants description, arrests him, and seizes the cocaine.

Did the agent have probable cause to arrest and search the man without a warrant? Could the evidence be admitted in the man’s trial? In a similar case, the Supreme Court ruled that the arrest was appropriate and the evidence admissible.

Vehicles present another exception to the search warrant requirement. Because they can easily be moved, hidden, or even destroyed, evidence could be permanently lost if a police officer, again acting under “probable cause,” was not able to search a vehicle at the time it is stopped. So long as the search is made in connection with an otherwise lawful traffic stop, the Court has allowed probable cause searches of cars, trucks, and other vehicles.

Another instance in which evidence can be seized without a warrant is when a police officer is in “hot pursuit” of a suspect. If the suspect enters his or her home, the officer is free to follow them in, make an arrest, and seize whatever evidence is found there. Finally, consistent with its recent emphasis on the need to establish order and control crime, the Court has ruled that evidence obtained in “good faith,” although in violation of the Fourth Amendment, may, under certain circumstances, still be admissible in a court of law.