There is a good reason that the Justice Department has always taken the position that presidents should abide by the provisions of the Ethics in Government Act, even though they are exempted from it for constitutional reasons: Doing that saves the president and his administration a lot of potential troubles. But President-elect Donald Trump’s announcement Wednesday that he will retain full personal ownership of the Trump Organization’s hundreds of companies and worldwide business interests, while setting up a structure for his children and trusted executives to manage the organization, invites just the sort of trouble the law is designed to avoid. Trump made the point that nothing legally prevented him from running his business from the Oval Office. That’s true, but it is also a red herring: He is smart enough to know that we hoped. Trump was elected president to concentrate on the demands of the office, which have overwhelmed some of its occupants. So he did not have a practical option — he had to turn the running of the business over to someone else while he concentrates on “making America great again.” The question before now, however, was whether Trump would take a path that would free him and his administration from battles over conflicts of interest and the appearance of acting to enrich himself from the White House. And he chose not to do so.