Not long ago, the idea that a former president—or major-party presidential nominee—would face serious legal jeopardy was nearly unthinkable. Today, merely keeping track of the many cases against Donald Trump requires a law degree, a great deal of attention, or both. In all, Trump faces 91 felony counts across two state courts and two different federal districts, any of which could potentially produce a prison sentence. He’s also dealing with a civil suit in New York that could force drastic changes to his business empire, including closing down its operations in his home state. Meanwhile, he is the leading Republican candidate in the race to become the next president. If the court cases unfold with any reasonable timeliness, he could be in the heat of the campaign trail at the same time that his legal fate is being decided. David A. Graham: The end of Trump Inc. Here’s a summary of the major legal cases against Trump, including key dates, an assessment of the gravity of the charges, and expectations about how they could turn …