Barron’s editorial page editor Thomas Donlan pans the leading presidential candidates’ approach to trade policy.

On anniversaries of the Declaration of Independence, we celebrate our inalienable rights to life, liberty, and the pursuit of happiness. Too many Americans, however, talk as if the right to pursue happiness implies a government guarantee of success.

Every few decades, Americans seek to secure happiness with restrictions on immigration and trade.

Donald Trump, for example, wants to weasel out of the North American Free Trade Agreement because it creates economic efficiency and shares the benefits with Mexicans and Canadians.

“I’m going to tell our Nafta partners that I intend to immediately renegotiate the terms of that agreement to get a better deal for our workers,” Trump said last week. “And I don’t mean just a little bit better, I mean a lot better. If they do not agree to a renegotiation, then I will submit notice…that America intends to withdraw from the deal.”

The president has that self-destructive power, though exercising it would be an easy way to raise prices and destroy jobs other than those it would protect. …

… Hillary Clinton deserves some blame, but it’s not for supporting Nafta as First Lady decades ago. It’s for sounding too much like Trump in the present. She has gone to the dark side on the Keystone XL Pipeline and the Trans-Pacific Partnership, which she thought advantageous before running for president this year.

In her speech on the economy, she promised to appoint a “trade prosecutor” and to go after “unfair trade practices, like when China dumps cheap steel in our markets.”

A trade prosecutor? Is that a cop who arrests Americans for engaging in international business? It would be a perfect title for Trump’s trade emissary. And it’s a lot more ominously believable when he says it. But it’s not sensible: There are more steel-using industries in the U.S. than steel makers, and many of the users depend on cheaper steel from abroad (not just China). Cheap steel is a gift to the U.S. economy and its consumers.