As Donald Trump fights a mountain of criminal charges, a separate battle over his eligibility to run for president in 2024 is fast emerging.The US constitution sets out just a handful of explicit requirements someone must meet to be the president. They must be at least 35 years old, a “natural-born” citizen, and a United States resident for at least 14 years. The constitution also bars someone who has served as president for two full terms from running again.None of those requirements disqualify Trump, or anyone else charged with a crime, from running for federal office.But one provision in the...