The case of a 23-year-old American photographer, tried Saturday on charges of drug smuggling, has hightlighted differences between the legal systems and national customs of Spain and the United States. Conan Owen, a 1986 graduate of Syracuse University, was charged with smuggling more than four pounds of cocaine from Chile to Spain in a false-bottomed suitcase. He received the suitcase from a travel agent near his home in Annandale, Va. Both prosecuting attorney Teresa Calvo, who asked for a 10-year jail sentence, and presiding Judge Jose Presencia Rubio expressed incredulity that a university graduate would accept a job from a passing acquaintance and agree to carry a suitcase halfway around the world for someone he hardly knew. In Spain, the custom is only to do business with people you know. During his year in Barcelona's 85-year-old Model Prison, Owen said he didn't understand why he had not been freed on bail pending trial. Bail was denied because Owen was a foreigner caught with a substantial amount of relatively pure cocaine. When U.S. law enforcement agents testified Saturday that Owen had provided them with information leading to a half dozen indictments of members of a suspected cocaine smuggling ring, the judge called it all ``very interesting'' but said he was only interested in Owen's case. Attorney General Edwin Meese III even delivered copies to Spanish judicial authorities of a statement made by George Barahona, the man who hired Owen, and who early last month received a two-year suspended sentence for narcotics violations from a federal court in Virginia. In the statement made in a plea bargain agreement, Barahona said Owen knew nothing about the drugs and had been used as a carrier. But plea bargaining does not exist in Spain. In her summary, Calvo implied that plea bargaining was a less-than-honorable institution. U.S. officials faced a similar problem several years ago when a Spanish court was considering U.S. and Spanish requests for extradition of Colombian cocaine baron Jorge Luis Ochoa Vasquez. The U.S. indictment of Ochoa, who was arrested in Madrid in November 1984, was based on extensive testimony obtained through a plea bargin. The Spanish court instead sent Ochoa back to Colombia in July 1986. He went free a week later.