Parallel litigation is difficult to define and sometimes means what the speaker wants it to mean. It may be limited to identical lawsuits with exactly the same parties and the same claims. It may also mean any instance of two or more lawsuits that may result in claim preclusion for some or all of the parties. It includes concepts of reactive and repetitive litigation, related litigation, and derivative litigation. Whatever it is thought to encompass, it incurs criticism as being vexing and harassing, wasteful of the parties\u27 and courts\u27 resources, and inclined to produce inconsistent results and possibly inter-governmental discord. At the same time, it is a prime example of the long tradition of forum shopping and is a useful tool for...