Tonight on The Last Word: A new court filing shows that Fox News lawyers were concerned about claims being made on air by Fox hosts. Plus, MI Rep. Elissa Slotkin joins Lawrence O'Donnell to discuss her newly announced Senate run in 2024. Also, Treasury Sec. Janet Yellen makes a surprise visit to Ukraine. And Mehdi Hasan explains how to "win every argument." Rep. Adam Schiff, Rep. Elissa Slotkin, Ben Rhodes, and Mehdi Hasan join Lawrence O'Donnell.