Two approaches to state law in federal courts that have been used throughout U.S. history.  Under the old test, the federal courts applied federal common law to claims that did not arise under a federal statute.  In this way, the substantive law would be the same, regardless of which federal court the plaintiff filed suit in.  However, the law may change is the case is litigated in the state court system instead of the federal court system. 

Under the modern approach, however, the federal court will apply the substantive law of the state in which the court sits.  In this way, the law will be the same regardless of whether the case is filed in state or federal court.  However, the law may change if the case is litigated in a different state. 

Which system do you think is best and why?Explain