The Navy Distinguished Service Medal is awarded to a person who, while serving in any capacity with the Navy or Marine Corps, distinguishes himself by exceptionally meritorious service to the United States in a duty of great responsibility. To justify this decoration, an exceptional performance of duty, clearly above that normally expected, which has contributed materially to the success of a major command or project, is required. In general, the Distinguished Service Medal will be awarded only to those officers in principal commands at sea or in the field whose service is such as to justify the award. However, this shall not be interpreted to preclude the award of the Distinguished Service Medal to any individual whose service meets the requirements. If there is any doubt as to the degree of service involved, the Legion of Merit is the more appropriate award.