Patchwork international regulations govern cargo ships like the one that toppled Baltimore bridge

Critics say the patchwork system of safety regulations governing massive cargo ships like the one that toppled a Baltimore bridge this week can allow shippers to skirt oversight. That's why one safety expert called maritime shipping “the weakest link in the transportation system.” The thousands of container ships that carry more than 80% of all goods moved around the world are governed by rules established by an international organization that are enforced by the various countries where ships are based and ports. Many ships are flagged in “countries of convenience” that offer cheap registration fees but may not have robust oversight. Former National Transportation Safety Board Chairman Jim Hall says there isn't a strong safety infrastructure in maritime.