Gavin Newsom, meet John Calhoun. The Coast governor echoes the 19th-century backer of “nullification” by stoking defiance of President Trump’s tariffs. He vows to “fight back” against the new tariffs by forging “strategic partnerships with international trading partners” and pleading for “California-made products to be excluded” from any “foreign retaliatory measures.” Has Mr. Newsom forgotten his oath to the United States Constitution?