DNC's Tom Perez: We were hacked, and we need to seek justice

In a lawsuit filed Friday, the Democratic National Committee alleges President Trump’s campaign, WikiLeaks and the Russian government took part in a massive plot to interfere in the 2016 presidential election by releasing stolen DNC emails. Why file the lawsuit while special counsel Robert Mueller is still investigating? DNC chairman Tom Perez joins Judy Woodruff to discuss the decision.