Donald Trump's tariff war is facing its biggest legal challenge yet this week. The Supreme Court will hear arguments challenging the legality of many of his administration's tariffs. The World Trade Organization is paying close attention to this legal challenge and Christiane sat down with its Director-General Ngozi Okonjo-Iweala in London. 

Also on today's show: Wolf Blitzer on the death of Dick Cheney; Atlantic CEO Nicholas Thompson; Michael Sandel, Winner, Berggruen Prize for Philosophy & Culture