Query: What is a major implication of the Erie doctrine?
Context: The other major implication of the Erie doctrine is that federal courts cannot dictate the content of state law when there is no federal issue (and thus no federal supremacy issue) in a case. When hearing claims under state law pursuant to diversity jurisdiction, federal trial courts must apply the statutory and decisional law of the state in which they sit, as if they were a court of that state, even if they believe that the relevant state law is irrational or just bad public policy.