A multi-district litigation (MDL) is a mechanism that allows one federal court to handle multiple similar cases at the same time. Courts often rely on MDLs in dangerous drug cases since there are thousands of plaintiffs with similar complaints. MDLs temporarily consolidate these cases during the pretrial stage. Then the judge will permit a few of them - usually four or five - to go to trial. These are called bellwether trials. How these bellwether trials turn out sets the stage for future negotiations. After the bellwether trials, the defense attorneys begin a period of negotiation with the plaintiffs' attorneys. If the bellwether plaintiffs won and got a big verdict, the defendants will likely offer large settlements to the remaining plaintiffs. If the bellwether plaintiffs lost or won a small verdict, the defendants will likely offer modest settlements or none at all. MDLs usually take a few years from start to finish.