Opinion of the Court. Mr. Charles J. Greene for plaintiff in error. Mr. Ralph W. Breckenridge was on his brief. Mr. W. J. Connell for defendant in error. MR. JUSTICE SHIRAS, after stating the case, delivered the opinion of the court. The motion to dismiss the writ of error, on the ground that the rights and immunities of the plaintiff in error under the Constitution of the United States were not set up or claimed in the state courts at the proper time and in the proper way, cannot be allowed. This subject has been so frequently and so recently discussed by this court that it is unnecessary for us to further consider it at large. It is sufficient to say that this record discloses that the plaintiff in error, in its answer to the writ of mandamus issued out of the district court of Douglas County, State of Nebraska, claimed that by reason of certain provisions of its charter, of general laws of the State, and of ordinances of the city of Omaha, all of which were specifically set forth, a contract was created between the plaintiff in error and said city in respect to the viaduct in question, the obligations whereof would be violated by the proposed enforcement of the subsequent act of 1887, contrary to the provisions of the Constitution of the United States; that the district court held that the laws and ordinances so pleaded did not create a contract between the State and city on the one side and the plaintiff in error on the other; that the plaintiff in error, in its petition in error to the Supreme Court of the State, specifically assigned as error the holding of the trial court that the said laws, charter and ordinances did not constitute a contract within the meaning and protection of the Constitution of the United States, guaranteeing the inviolability of contracts; and that the Supreme Court of the State, in its opinion disposing of the case, states that "the most important subject of inquiry is presented by respondent's contention that the ordinance under which the city proceeded in ordering the repairs Opinion of the Court. in question contemplates the taking of its property without due process of law within the meaning of the state and Federal constitutions, and also impairs the obligation of the contract under which its track was laid and under which said viaduct was constructed." We think it is plain, from this recital, that a Federal question was specifically presented in both the trial and Supreme courts of the State. As the record further discloses that the state Supreme Court overruled the railroad company's contention that it held an existing contract whose obligation would be violated by the enforcement of the provisions of a subsequent law of the State, it becomes the duty of this court to inquire whether there was error in that judgment of the Supreme Court of the State. We have often had occasion to say that this court, when reviewing the final judgment of a state court upholding a state enactment alleged to be in violation of the contract clause of the Constitution, possesses paramount authority to determine for itself the existence or the non-existence of the contract set up, and whether its obligation has been impaired by the state enactment. Jefferson Branch Bank v. Skelly, 1 Black, 436; Railroad Co. v. Rock, 4 Wall. 177; New Orleans Waterworks v. Louisiana Sugar Co., 125 U. S. 18; Mobile & Ohio Railroad v. Tennessee, 153 U. S. 486, 492. We shall proceed, therefore, to examine whether the statutes and ordinances to which the plaintiff in error points us constituted a contract within the protection of the Constitution of the United States, and whether such contract, if found to exist, has been impaired by the subsequent statute and the proceedings thereunder. The contract, which the plaintiff in error sets up as constitutionally protected from subsequent legislation, is alleged to be found in the act of March 4, 1885, and the agreement in compliance with the provisions of that act between the city of Omaha, the Union Pacific Railway Company and the Omaha and Southwestern Railroad Company on the first day of February, 1886. Opinion of the Court. By the provisions of the act the mayor and city council in any city of the first class were authorized, whenever they deemed it necessary for the safety and convenience of the public, to engage and aid in the construction of any viaduct, or bridge over, or tunnel under any railroad track or tracks, switch or switches, in such cities, when such track or switches cross or occupy any street, alley or highway thereof; to adopt and secure plans and specifications therefor, together with the estimated cost of the work, and thereupon, if the railroad company or companies, across whose tracks or switches the work is proposed to be built, will assume three-fifths of all damages to abutting property on account of the construction of said viaduct, bridge or tunnel, and secure to the city the payment of the necessary funds to meet it as the work progresses, in such manner and with such security as the mayor and city council shall require; and when the payment of the further sum of one-fifth of the money required for said improvement is arranged for in manner satisfactory to said mayor and council, either by private donations or by execution of such good and sufficient bonds as will protect said city from the payment of said one-fifth, then the said mayor and council may proceed to contract with the necessary party or parties for the construction of such viaduct, bridge or tunnel, under the supervision of the board of public works of such city, and to provide for the payment of one-fifth of the cost thereof by the city, by special tax on all taxable property in such city, and one-fifth by special tax on property benefited. It was further provided that the city, with the assent of the railroad company or companies aiding in the construction of any such viaduct, bridge or tunnel, may permit any street railway company to build its street railway track and operate its railway upon or through the same, upon such terms and conditions and for such compensation as shall be agreed upon. between the city and the street railway company; and that the compensation for such use shall be set apart and used towards the maintenance of such viaduct, bridge or tunnel; and it was further provided that the mayor and council of any such city should have the power to pass any and all ordi Opinion of the Court. nances, not in conflict with the act, that might be necessary or proper for the construction, maintenance and protection of the works provided for. The agreement made, in pursuance of the said act, between the city of Omaha, as party of the first part, and the Union Pacific Railway Company and the Omaha and Southwestern Railroad Company, as parties of the second part, provided that the parties of the second part assumed and agreed to pay, as should be required by the mayor and city council, three fifths of the entire cost of constructing a viaduct along Eleventh street in said city over the railroad tracks of the said second parties, and three fifths of the damages to abutting property on account of the construction of such viaduct, not otherwise provided for by waivers or private contributions; such entire cost and damages not to exceed the sum of ninety thousand dollars; and that the amount so assumed and agreed to be paid, being three-fifths of the entire cost and damages, was to be apportioned between the railroad companies, so that three fourths thereof should be paid by the Union Pacific Railway Company and one fourth by the Omaha and Southwestern Railroad Company. Under this agreement the viaduct was built and formally opened to the use of the public early in the year 1887. By an act approved March 30, 1887, c. 10, Laws of Nebraska, 1887, 105, entitled "An act incorporating metropolitan cities, and defining, regulating and prescribing their duties, powers and government," it was, among other things, provided as follows: "The mayor and council shall have power to require any railroad company or companies, owning or operating any railroad track or tracks upon or across any public street or streets of the city, to erect, construct, reconstruct, complete and keep in repair any viaduct or viaducts upon or along such street or streets, and over or under such track or tracks, including the approaches to such viaduct or viaducts as may be deemed and declared by the mayor and council necessary for the safety and protection of the public. When two or more railroad companies own or operate separate lines of track to be crossed by any such viaduct, the Opinion of the Court. proportion thereof, and of the approaches thereto, to be constructed by each, or the cost to be borne by each, shall be determined by the mayor and council. After the completion of any such viaduct, any revenue derived therefrom by the crossing thereon of street railway lines, or otherwise, shall constitute a special fund, and shall be applied in making repairs to such viaduct. All ordinary repairs to any such viaduct or to the approaches thereto, shall be paid out of such fund, or shall be borne by the city." In 1893 another act was passed, c. 3, Laws of Nebraska, 1893, 70, amending the act of 1887, and making it the duty of any railroad company or companies to erect, construct or repair any viaduct in the manner required by the mayor and council, providing a penalty for neglect or refusal to perform such duty, and prescribing a proceeding by mandamus to compel the companies to erect or repair any viaduct as may be required by ordinance, and empowering the city, in case of failure or refusal by the railroad companies, itself to do the necessary work, the cost thereof to be a charge and lien upon the property of the railroad companies, and also to be a legal indebtedness of the companies, collectible by suit in the proper court. On January 30, 1894, the city council passed an ordinance requiring the Union Pacific Railway Company to repair that portion of the said Eleventh street viaduct for a distance of two thirds of the entire length of the viaduct, and the Chicago, Burlington and Quincy Railroad Company, as grantee and successor of the Omaha and Southwestern Railroad Company, to repair the other one third portion of said viaduct, said repairs to be made in accordance with plans furnished by the city and under the supervision of the city engineer, and to be completed within ninety days. And upon the refusal of the companies to comply with said ordinance separate proceedings in mandamus were brought against them. No doubt the agreement of 1886 constituted a contract, in such a sense that the respective parties thereto continued to be bound by its provisions so long as the legislation, in virtue of which it was entered into, remained unchanged. While the agreement lasted its provisions defined the rights and duties |