Louis Brandeis

“ The doctrine rests upon the assumption that there is "a transcendental body of law outside of any particular State but obligatory within it unless and until changed by statute," that federal courts have the power to use their judgment as to what the rules of common law are ”

“ It contended, among other things, that its duty to Tompkins, and hence its liability, should be determined in accordance with the Pennsylvania law; that under the law of Pennsylvania, as declared by its highest court, persons who use pathways along the railroad right of way-that is, a longitudinal pathway as distinguished from a crossing-are to be deemed trespassers; and that the railroad is not liable for injuries to undiscovered trespassers resulting from its negligence, unless it be wanton or willful. ”

“ The common law so far as it is enforced in a State, whether called common law or not, is not the common law generally but the law of that State existing by the authority of that State without regard to what it may have been in England or anywhere else. ”

“ Barber v. Pittsburg, F.W. & C. R. Co., 166 U.S. 83, 99–100; Messinger v. Anderson, 171 Fed. 785, 791–92 (C.C.A.6) , reversed on other grounds, 225 U.S. 436; Knox & Lewis v. Alwood, 228 Fed. 753 (S.D. Ga.) . ”

“ L. Q. 499, 524–30; Johnson, State Law and the Federal Courts (1929) 17 Ky. L. J. 355; Fordham, The Federal Courts and the Construction of Uniform State Laws (1929) 7 N.C. L. Rev. 423; Dobie, Seven Implications of Swift v. Tyson (1930) 16 Va. L. Rev. 225; Dawson, Conflict of Decisions between State and Federal Courts in Kentucky, and the Remedy (1931) 20 Ky. L. J. 1; Campbell, Is Swift v. Tyson an Argument for or against Abolishing Diversity of Citizenship Jurisdiction (1932) 18 A.B.A.J. 809; Ball, Revision of Federal Diversity Jurisdiction (1933) 28 Ill. L. Rev. ”