Throughout the early history of the American legal system, if you wanted to sue anyone in court you had to follow this arcane and inconsistent labyrinth of common law pleading rules. What we today generically call “lawsuits” were pointlessly split up into “actions at law” or “bills in equity” or whatever else, all of which had different pedantic rules depending on the jurisdiction you’re in (for a long time, federal courts dealing with state law had to apply procedural rules that were in effect