Which of the following prevents a Marine from being promoted?

The reason a pending court-martial or non-judicial punishment can prevent a Marine from being promoted relates directly to the standards of conduct and readiness expected in the Marine Corps. When a Marine is facing a court-martial or has received non-judicial punishment (NJP), it signifies that they have potentially violated military law or regulations. This situation raises questions about their reliability, judgment, and overall suitability for promotion. Promotions within the Marine Corps are contingent upon an individual's performance and conduct; therefore, any pending legal actions create a significant concern regarding the Marine’s professionalism and adherence to the values of the Corps. This makes them ineligible for promotion until these issues are resolved.

On the other hand, participation in advanced training courses, being assigned to special duty, or completing all required training typically reflect positively on a Marine. These experiences can enhance skill sets or demonstrate commitment, and usually contribute to eligibility for promotion rather than detracting from it. Hence, while the other factors can contribute to a Marine's development and readiness, they do not act as barriers like pending legal issues do.