Criminal law should be clear so that those covered by it can understand what is permitted and what is prohibited. It’s not the place for creative interpretations by the judiciary or partisan prosecutors. Jack Smith has now dropped his cases against president-elect Donald Trump on the grounds that a president cannot be criminally prosecuted, but there is much more that made these prosecutions untenable: They were never grounded in any fair reading of the law that Smith relied upon. The two cases involved Trump’s handling of classified material and his purported efforts to overturn the results of the 2020 election....