A class action claim is when a group of people file a complaint against a defendant, or group of defendants, for a similar grievance. A personal injury claim is smaller and usually only involves one or two plaintiffs taking action against a defendant, or defendants. The rules governing how each type of action is filed vary greatly as well. For example, in order for a group to file a class action suit, the group must share similar circumstances, injuries and damages against the defendant(s). There are other important requirements depending on the size of the class. In some circumstances, federal law applies under the Class Action Fainess Act. In contrast, a typical personal injury claim usually involves only state law.