John Marshall Harlan II

“ It must be obvious that the fraction of a railroad's lines located within Pennsylvania is wholly unilluminating as to the consistency with which that railroad used appellant's cars in some other State. ”

“ In this case we must decide whether the Commonwealth of Pennsylvania may, consistently with the Commerce Clause and the Due Process and Equal Protection Clauses of the Fourteenth Amendment to the Constitution of the United States, impose an annual property tax on the total value of freight cars owned by the appellant, a Pennsylvania corporation, despite the fact that a considerable number of such cars spend a substantial portion of the tax year on the lines of other railroads located outside the State. ”

“ It is not disputed that many of the railroads listed as owning no track within Pennsylvania do have lines in more than one State, but there is no way of knowing which, if any, of these States may have acquired taxing jurisdiction over some of appellant's freight cars. And even with respect to railroads whose lines do not extent beyond the borders of a single State, it cannot be determined whether their use of appellant's cars was habitual or merely sporadic. ”