50. What agency is responsible for enforcing the rules for obstruction lights on mobile offshore drilling units?

The U.S. Coast Guard enforces regulations for mobile offshore drilling unit obstruction lights. These units are regulated as vessels under 46 CFR Subchapter I-A, and the Coast Guard administers and enforces these regulations, including lighting and marking requirements for navigation safety. Other agencies, such as the Department of Energy, Corps of Engineers, and Minerals Management Service, have different roles and do not enforce these specific regulations.