SPRINGFIELD — The Illinois Supreme Court heard arguments in a case questioning whether a counterclaim challenging the constitutionality of a law can continue even if the plaintiff’s underlying lawsuit is dismissed for lack of a cause of action.In 2010, railroad employee Mary Carmichael was a passenger in a van owned and operated by Professional Transportation Inc. when she was injured in a collision.Her employer, Union Pacific, required employees to be transported between job sites by contract services like PTI …