"Unless the writ of mandamus is to become practically valueless, and is to be refused even where a public officer is commanded to do a particular act by virtue of a particular statute, this writ should be granted. Every statute to some extent requires construction by the public officer whose duties may be defined therein. Such officer must read the law, and he must therefore, in a certain sense, construe it, in order to form a judgment from its language what duty he is directed by the statute to perform. But that does not necessarily and in all cases make the duty of the officer anything other than a purely ministerial one. If the law direct him to perform an act in regard to which no discretion is committed to him, and which, upon the facts existing, he is bound to perform, then that act is ministerial, although depending upon a statute which requires, in some degree, a construction of its language by the officer. Unless this be so, the value of this writ is very greatly impaired. Every executive officer whose duty is plainly devolved upon him by statute might refuse to perform it, and when his refusal is brought before the court he might successfully plead that the performance of the duty involved the construction of a statute by him, and therefore it was not ministerial, and the court would on that account be powerless to give relief. Such a limitation of the powers of the court, we think, would be most unfortunate, as it would relieve from judicial supervision all executive officers in the performance of their duties, whenever they should plead that the duty required of them arose upon the construction of a statute, no matter how plain its language, nor how plainly they violated their duty in refusing to perform the act required." We therefore conclude that the Court of Appeals rightly directed that the writ be granted. Judgment affirmed. 244 U.S. Opinion of the Court. LEHIGH VALLEY RAILROAD COMPANY v. ERROR TO THE SUPREME COURT OF THE STATE OF NEW YORK. No. 194. Argued April 20, 1917.-Decided May 21, 1917. An employee is not engaged in interstate commerce, within the meaning of the Federal Employers' Liability Act, when his work at the time of injury consists in placing cars owned by the carrier, containing its supply coal, upon an unloading trestle within its yards, and when the interstate movement of the cars carrying the coal occurred as long as seventeen days previously and the cars, with the coal, in the meantime, have remained upon sidings and switches in the yards. Chicago, Burlington & Quincy R. R. Co. v. Harrington, 241 U. S. 177. 214 N. Y. 116, reversed. THE case is stated in the opinion. Mr. Peter F. McAllister, with whom Mr. F. O. McCleary was on the briefs, for plaintiff in error. Mr. Clayton R. Lusk for defendant in error. MR. JUSTICE MCREYNOLDS delivered the opinion of the court. Basing his claim upon the Federal Employers' Liability Act, defendant in error sought damages for personal injuries. The New York Court of Appeals affirmed a judgment in his favor, 214 N. Y. 116, and the question now presented is whether there is evidence tending to show that he was injured while engaging in interstate commerce. The accident occurred July 27, 1912, when, as member of a switching crew, he was assisting in placing three cars containing supply coal for plaintiff in error on an unloading trestle within its yards at Cortland, New York. These cars belonged to it and with their contents had passed over its line from Sayre, Pennsylvania. After being received in the Cortland yards-one July 3 and two July 10— they remained there upon sidings and switches until removed to the trestle on the twenty-seventh. We think their interstate movement terminated before the cars left the sidings, and that while removing them the switching crew was not employed in interstate commerce. The essential facts in Chicago, Burlington & Quincy R. R. Co. v. Harrington, 241 U. S. 177, did not materially differ from those now presented. There we sustained a recovery by an employee, holding he was not engaged in interstate commerce; and that decision is in conflict with the conclusion of the Court of Appeals. The judgment under review must be reversed and the cause remanded for further proceedings not inconsistent with this opinion. Reversed. SMITH ET AL. v. THIRD NATIONAL EXCHANGE BANK OF SANDUSKY, OHIO, ET AL. ERROR TO THE SUPREME COURT OF THE STATE OF NEW MEXICO. No. 214. Argued April 24, 25, 1917.-Decided May 21, 1917. Where lands, allotted as part of a Mexican community grant and for many years occupied, improved and claimed in good faith under color of such allotments and mesne conveyances, were excluded from the grant by a decree of the Court of Private Land Claims determining its boundaries, Held, that a continuance of such occupancy under the same and later mesne conveyances, with knowledge of the decree, was not a trespass of the character forbidden by the act to prevent unlawful occupancy of public lands (February 25, 1885, c. 149, 23 Stat. 321), but came within the exceptions of that act as an occupancy under claim and color of title made or acquired in good faith. 20 N. Mex. 264, affirmed. THE case is stated in the opinion. Mr. F. G. Morris, with whom Mr. W. B. Grant was on the briefs, for plaintiffs in error. Mr. W. H. Winter, with whom Mr. A. Seymour Thurmond, Mr. J. H. Paxton and Mr. R. L. Young were on the brief, for defendants in error. MR. JUSTICE MCREYNOLDS delivered the opinion of the court. Defendants in error brought suit in the District Court, Dona Ana County, New Mexico, seeking judgment against plaintiff in error Smith upon his three notes for forty-five hundred dollars ($4,500) each and also foreclosure of the mortgage upon lands in that county given to secure them. Recovery was resisted upon the ground that although Smith was in actual possession of the lands under deed from Reinhart they belonged to the United States and were unlawfully in the vendor's possession when so conveyed without bona fide claim or color of title, contrary to the Act of Congress approved February 25, 1885, 23 Stat. 321; and that the notes were given in part payment therefor. The state Supreme Court affirmed a judgment in the bank's favor. Quotations from its statement will suffice to indicate the essential facts (20 N. Mex. 264): "In 1851 the government of Mexico granted certain lands now embraced within the limits of Dona Ana County, this state, to the Colony of Refugio. The grant was similar to many others found in this state. Settlements were made upon it by many people, and individual allotments were made from time to time by the commissioners. "The territorial legislature, by the Act of March 7th, 1884, constituted the owners of lands within the limits of the grant a body corporate and politic under the name and style of the Grant of the Colony of Refugio, under which they were authorized by said act to sue and be sued and have perpetual succession. "Many years ago the lands involved in this litigation, embracing some 400 acres were allotted to ten individuals, who subsequently, by separate deeds of conveyance, transferred the same to Leon Alvarez, probably some time in the 80's, but the date is wholly immaterial. From that time to 1909 various deeds were executed to divers parties, all of whom had possession and cultivated and improved the lands. Something like six or seven thousand dollars, possibly more, have been expended in improvements on the land in constructing irrigation ditches. In 1909 W. H. Reinhart claimed to be the owner of the lands, under deeds of conveyance, and was in possession of the same. In that year he conveyed the same to D. B. Smith, the appellant here, receiving perhaps one-half of the purchase money in cash, and to secure the balance took Smith's promissory notes, secured by a mortgage on the real estate. The notes aggregated $13,500.00. It is not disputed that Reinhart was the owner of said lands if the original allottees were invested with the legal title to the same. "Some time prior to 1893, the grant was surveyed by Elkins & Marmon, and the lands in question here were within the limits of that survey. In 1893, the commissioners of the grant, acting under the power and authority conferred by the Act of March 7, 1884, instituted proceedings in the United States Court of Private Land Claims to have the title of said grant confirmed and settled. Leon Alvarez was one of the commissioners of the grant |