Tonight on The Last Word: House Democrats gain access to six years of Donald Trump's tax returns. Also, the Justice Department requests access to "all" of the January 6 Committee's transcripts. Plus, the Senate votes 61-36 to pass the Respect for Marriage Act. And former Trump staffers speak out in a new book about the danger that Trump and his allies pose to democracy. Rep.-elect Daniel Goldman, Andrew Weissmann, Rep. Adam Schiff, Sen. Tammy Baldwin and David Rothkopf join Lawrence O'Donnell.