system: You are a legal assistant. Answer concisely and accurately. When legal text is provided, rely on it and do not invent facts.

user: Read the following U.S. Supreme Court case excerpt and classify it into the correct legal issue area. Excerpt: 355 U.S. 175 78 S.Ct. 189 2 L.Ed.2d 183 INTERSTATE COMMERCE COMMISSION, Appellant,v.BALTIMORE & OHIO RAILROAD COMPANY et al. The PENNSYLVANIA RAILROAD COMPANY, Appellant, v. The BALTIMORE & OHIO RAILROAD COMPANY et al. ERIE RAILROAD COMPANY and the Port of New York Authority, Appellants, v. The BALTIMORE & OHIO RAILROAD COMPANY et al. The NEW YORK CENTRAL RAILROAD COMPANY, Appellant, v. The BALTIMORE & OHIO RAILROAD COMPANY et al. ARMCO STEEL CORPORATION, M. A. Hanna Company, Iron Ore Company of Canada, Appellants, v. The BALTIMORE & OHIO RAILROAD COMPANY et al. DELAWARE RIVER PORT AUTHORITY, City of Philadelphia, Chamber of Commerce of Greater Philadelphia, Appellants, v. The BALTIMORE & OHIO RAILROAD COMPANY et al. UNITED STATES of America, Appellant, v. The BALTIMORE & OHIO RAILROAD et al. Nos. 463—468, 473. Decided Dec. 9, 1957. Motion to Clarify Judgment Denied June 2, 1958, 356 U.S. 970, 78 S.Ct. 1133. Messrs. Robert W. ginnane and Issaac K. Hay, Washington, D.C., for appellant Interstate Com. Com'n. Messrs. Guernsey Orcutt, Richard R. Bongartz, Philadelphia, Pa., and William Pepper Constable, Baltimore, Md., for appellant Pennsylvania R. Co. Messrs. Sidney Goldstein, New York City, Francis A. Mulhern, Newark, N.J., Arthur L. Winn, Jr., J. Stanley Payne and Samuel H. Moerman, Washington, D.C., for appellants Erie R. Co. and others. 1 Messrs. Robert D. Brooks, New York City and Richard J. Murphy, Chicago, Ill., for appellant New York Cent. R. Co. 2 Mr. John F. Donelan, Washington, D.C., for appellants Armco Steel Corp. and others. 3 Mr. Warren Price, Jr., Washington, D.C., for the Delaware River Port Authority. 4 Mr. David Berger, Philadelphia, Pa., for the City of Philadelphia. 5 Mr. Frederick, H. Knight, Philadelphia, Pa., for the Chamber of Commerce of Greater Philadelphia. 6 Solicitor General J. Lee Rankin, Victor R. Hansen, Asst. Atty. Gen., and Mr. Daniel M. Friedman, Washington, D.C., for the United States. 7 Edwin H. Burgess, Anthony P. Donadio, Norman C. Melvin, Jr., William C. Purnell and Jervis Langdon, Jr., Baltimore, Md., for the Baltimore & Ohio Railroad Co. and others. 8 William L. Marbury, Baltimore, Md., for the Maryland Port Authority. 9 Harry C. Ames, Washington, D.C., and Charles McD. Gillan, Baltimore, Md., for Baltimore Association of Commerce. 10 Mr. Francis D. Murnaghan, Jr., Baltimore, Md., for the Canton Railroad Co. 11 Mr. Thomas N. Biddison, Baltimore, Md., for Mayor and City Council of Baltimore. 12 PER CURIAM. 13 This litigation involves the validity of an order of the Interstate Commerce Commission dealing with the proper relationship, under the National Transportation Policy (§ 1 of the Transportation Act of 1940, 54 Stat. 899, 49 U.S.C., at p. 7107, 49 U.S.C.A. note, preceding section 1), of railroad tariffs on imported iron ore shipped to a steel-producing area in Pennsylvania, Ohio, and West Virginia (the so-called 'differential territory' of the Central Freight Association) from the ports of New York, Philadelphia, and Baltimore. A tariff differential in favor of Baltimore had existed prior to this controversy. In a succession of tariff reductions, railroads serving New York and Philadelphia filed schedules designed to establish parity of rates among the several ports, while railroads serving Baltimore filed schedules designed to maintain the differential. Upon protest against the New York and Philadelphia schedules by Baltimore civic and commercial interests and railroads serving that port, the Interstate Commerce Commission instituted an investigation as a result of which Division 2 of the Commission filed a report approving the tariff schedules giving Philadelphia parity with Baltimore but finding all other schedules that had been issued in this series of reductions to be not just and reasonable. 291 I.C.C. 527. On petition of various parties, the Commission reopened the proceedings, and on October 1, 1956, the full Commission modified the findings of the Division 2 report to the extent of finding the New York schedules, as well as the Philadelphia schedules, to be just and reasonable, 299 I.C.C. 195. The full Commission's order was challenged in a proceeding instituted under 28 U.S.C. § 1336, 28 U.S.C.A. § 1336, and an appropriate District Court held that the Commission's approval of parity between New York and Baltimore was without basis in the record and ordered that portion of the Commission's order vacated. The court further held that the Commission's approval of parity between Philadelphia and Baltimore was not supported by essential findings as to ocean freight costs and anticipated traffic and remanded that portion of the Commission's order for more explicit findings. The court also granted other relief subsidiary to these actions. Baltimore & O.R. Co. v. U.S., D.C., 151 F.Supp. 258. These are the only portions of the decision below with which we are here concerned. We put to one side those provisions of the decree below in which the District Court affirmed other portions of the Commission's order. 14 From what appears, it is not precluded that the Commission may find an interrelationship, within the purview of the National Transportation Policy, supra, among lawful tariffs to be established between these three ports and the 'differential territory.' In this light we deem it appropriate that, in reconsidering the relationship between the Philadelphia and Baltimore schedules pursuant to the remand of the District Court, the Commission should be free to reconsider and take action upon the New York schedules. In carrying out the District Court's direction regarding the Philadelphia rates, the Commission should be permitted to take into account the effect of New York rates on the tariff relationship between Philadelphia and Baltimore and the effect of that relationship on New York and to enter such orders with respect to all three ports as the Commission may find to be required by their interrelationship. Accordingly, on the appeals before us, so much of the decree of the District Court as did not affirm the order of the Commission is vacated, and the cause is remanded for appropriate disposition not inconsistent with this opinion. 15 The CHIEF JUSTICE and Mr. Justice BLACK would affirm the judgment of the District Court.

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