Opening salvos

PRESIDENT Donald Trump seems intent on starting a trade war, telling business executives he would punish companies that shut factories in the US and moved jobs overseas by imposing a “very major” border tax. Such a tax would probably be illegal under American law and would definitely violate treaties with other countries.

Congress has given the president authority to raise tariffs on imports in certain situations – as in war or during an international economic emergency. But that authority has not been used to take aim at the products of individual companies that moved manufacturing of their goods abroad.

Trump told a German newspaper that BMW might have to pay a 35 percent border tax on cars imported from a new factory in Mexico. In that case, BMW is not even moving production out of the US, but moving it from Germany, China and South Africa to Mexico. Experts say federal courts would most likely strike down such a tax if Trump tried to impose it. Even Congress might not have the authority to impose such taxes, because the constitution’s bills of attainder clause bars lawmakers from singling out businesses for punishment.

Foreign countries would almost certainly respond if Trump tried to impose a border tax.

In his inaugural speech, Trump railed against trade: “The wealth of our middle class has been ripped from their homes and then redistributed across the world.” But the protectionism he champions assumes trade provides no benefits. In fact, it brings Americans cheaper goods and drives economic growth and innovation.