Robert Mueller has a serious conflict of interest that should disqualify him from serving as special counsel. He has had a long and close relationship with someone who will surely become a pivotal witness –James Comey. No one doubts Mueller’s sterling credentials. That is not the issue. He is imminently qualified. The problem arises in his duty to fairly and objectively evaluate the evidence he gathers. How can Americans have confidence in the results if they know the special counsel may harbor a conspicuous bias? They cannot. The conflict inevitably discredits whatever conclusion is reached. It renders the entire investigatory...