Tonight on The Last Word: Ontario imposes a 25% tax increase on electricity exports to the U.S. in response to Donald Trump’s trade war. Also, Elon Musk attacks Sen. Mark Kelly’s visit to Ukraine. Plus, a federal judge partially blocks Trump from defunding USAID. And The New York Times reports a Justice Department official was fired after opposing restoring Mel Gibson’s gun rights. Sen. Amy Klobuchar, Sen. Adam Schiff, and Andrew Weissmann join Lawrence O’Donnell.