Friendly Illegality

When Ben first joined the police department, a long-standing friend in the same department told him that he would probably only have cop friends and that no one else understood police except other police. Ben felt uncomfortable about this and, together with his wife, made a conscious effort to find friends outside of the police force. They succeeded in part because Ben's wife, who was a teacher, was able to make friends from that profession. Nevertheless, Ben found that many people treated him differently than an ordinary citizen when they found out he was a policeman. They tended to blame him for all the troubles they encountered and especially for any citations they received from other police officers.

To deal with this problem, Ben and his wife decided not to tell any new acquaintances about his job. He would just say that he worked in public relations in the city, and after they became friends, then he would tell them what he really did. This seemed to work quite well, and after a while, Ben and his wife began to develop a circle of good friends. He found that these friends would alter their schedules to accommodate his shift work. For example, if a party was planned, Ben and his wife were contacted first to make sure that he would be available and could get the night off. Ben thought that some of these friends might be recreational drug users, but they always respected his position as a police officer, and he never observed them taking drugs in his presence.

Two friends, Jim and Sandy, invited Ben and his wife to dinner one Friday night, and when they arrived, Jim immediately gave Ben his favorite drink, which was scotch on the rocks. Jim put on some music, and Ben's wife went to help Sandy in the kitchen while Ben and Jim sat in the living room. Ben needed to put something under his drink so that he would not leave rings on the coffee table, and he saw a wooden box on the coffee table that looked the right size and shape to hold coasters. He reached out an opened the box. It did not contain coasters but several joints of marijuana. He put the lid back on the box, looked up, and saw fear in Jim's eyes.

Question: Assume that the possession of any quantity of marijuana is illegal in the municipality in which this event takes place. Using a utilitarian calculus what would be the right thing for Ben to do in this circumstance?