Trump’s statement that he may intervene in the case against Meng could be one of his most dangerous “break the norms” moments since he won the White House. By putting her arrest in play as a bargaining chip in trade talks, Trump has told the world that hostage-taking is now a part of his approach to international negotiations too. It also is a further erosion of the independence of the Justice Department. Trump has already demanded that it investigate his political foes, including Hillary Clinton, though so far the department has refused to follow his lead. It’s unclear how much it could resist him in the Meng case, but to swap her prosecution for a trade deal tells the world that U.S. arrest warrants can be made to go away if Trump gets a trade concession. While Trump may have the legal authority to intervene in a specific case, that he is willing to do so not for reasons of justice, but for political gain, is an appalling blurring of policy goals and our concept of an independent and professional Justice Department.