Donald Trump says he is for free trade. But it has to be fair trade. He sees himself not as a protectionist but as a protector of American workers from the ravages of unfair competition, somehow defined. In 1964 Supreme Court Justice Potter Stewart said when he was asked to define pornography, “I know it when I see it.” Trump knows unfair competition when he sees it. And he believes it is largely responsible for the $502 billion trade deficit the United States ran up last year, the largest in four years and 2.7 percent of GDP.

He sees a lot of the unfair trading coming from Mexico, with which he plans to negotiate major changes in the NAFTA trade agreement. Not so much from Canada, the third party to that agreement. He told visiting Prime Minister Justin Trudeau that their differences could be solved with a bit of “tweaking” since Canadians buy from us about as much as we buy from Canada—our trade is balanced. So the fact that identifies unfair trade might be the existence of a deficit in our dealings with that trading partner.