227 U.S. 59, 66, 33 S.Ct. 192, 57 L.Ed. 417 (1913) (“By this act Congress has undertaken to cover the subject of the liability of railroad companies to their employees injured while engaged in interstate commerce. This exertion of [the commerce] power which is granted in express terms must supersede all legislation over the same subject by the states.”); see also Winfield, 244 U.S. at 151, 37 S.Ct. 546 (“That [FELA] is comprehensive and also exclusive is distinctly recognized in repeated decisions of this court.”). However, because state courts have concurrent jurisdiction over FELA claims, FELA preempts state substantive law — but not state procedural law — in state court FELA actions. See Mondou v. N.Y., New Haven & Hartford R.R., 223 U.S. 1, 56-57, 32 S.Ct. 169, 56 L.Ed. 327 (1912) (<HOLDING>); see also Brown v. W. Ry. of Ala., 338 U.S.
holding that where state rules of civil procedure apply to courts of the state they do not apply to adjudicatory proceedings before state agencies holding that state courts in construing and interpreting state law are not bound by the decisions of federal courts holding that litigants may enforce fela in state courts as a matter of right but also observing that state courts are free to apply their own modes of procedure to fela cases holding that federal courts must apply state substantive law in diversity cases holding that state courts must apply the federal pleading standard in fela cases