 In these situations, the "Erie" doctrine requires the Federal court that acquires jurisdiction over cases governed in part by state law to apply the substantive law of the states.Generally, the "Erie" doctrine requires the Federal court to predict how the courts of a given state would rule and decide a given issue.Many states, however, allow certified questions to be addressed from the Federal court to the appellate court or state supreme court of that state, allowing the state court to decide those questions of law.