Tonight on The Last Word: President Biden calls for global unity in his last speech before the United Nations General Assembly. Also, a judge rules against Donald Trump in the January 6 case. Plus, legal experts detail the potential abuses of power after the Supreme Court gives Trump immunity. And 120 current and former Republican officials in Arizona endorse Vice President Kamala Harris. Andrew Weissmann, Melissa Murray, and Mayor John Giles join Lawrence O’Donnell.