'This is not a drill': Trump's Ukraine crisis tests govt system

06:42

President Trump is faces an impeachment investigation for allegedly criminally targeting a top domestic rival Joe Biden. MSNBC’s Chief Legal Correspondent Ari Melber analyzes how Trump’s response – threatening to criminally target his domestic rival Rep. Adam Schiff -- is “a test of the U.S. constitutional system of government.” Melber also reveals why the Ukraine scandal differs from the Mueller probe.