Courts in other states had heard cases raising similar claims and refused to certify a class on the grounds that there were too many individual differences among the plaintiffs. But the trial lawyers kept on forum shopping until they hit the Illinois jackpot....
Avery is also a classic example of regulation through litigation. That is, activist judges can bypass elected lawmakers to impose their own policy choices on people -- even, as in Avery, outside the judge's own jurisdiction.
In this case, most state insurance regulations permit the use of non-OEM parts and at least two require it. But the lower court ruling made new law for Illinois -- no non-OEM parts -- and effectively required insurance policies from the 47 other states covered in the class to be written in accordance with the Illinois regulation.