The Iran war has provided at least two clear economic lessons. It has exposed the steep costs of being reliant on fossil fuels, highlighting the need for countries to diversify their homegrown energy sources, including solar and wind power. And it has shown what US commerce could look like freed from the Jones Act, one of the most counterproductive protectionist measures of the last century.

The law, part of the Merchant Marine Act of 1920, requires vessels carrying cargo between American ports to be built, owned, flagged and predominantly crewed by Americans. To illustrate the problems this causes, consider this: A foreign-flagged ship coming from Asia can unload its goods at a West Coast port, but it cannot then pick up American-made goods and unload them at Honolulu — or any other US city. The act costs Hawaiian families $1,800 a year, according to one study. Alaskans and Puerto Ricans get walloped, too.

The act is not just a problem for those outside the continental US. All Americans pay for the inefficiencies it foists upon the shipping industry. By eliminating foreign competition for domestic shipping, the act drives up........

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