When the seven P&I clubs belonging to the International Group issued 72-hour cancellation notices for war risk coverage in the Persian Gulf on March 5, they did not just raise costs. They made transit impossible. P&I clubs insure roughly 90 percent of the world’s ocean-going tonnage. Without their coverage, ships cannot sail. Port authorities will not let them dock. Banks will not finance the cargo. Charterers will not book the vessel. The entire system, from loading berth to discharge terminal, is underwritten by a chain of contracts that begins with a club in London, Oslo, or Tokyo. When the clubs...