Opinion of the Court.

the law which permits the writ to issue where a mere ministerial duty is imposed upon an executive officer, which duty he is bound to perform without any further question. If he refuse under such circumstances, mandamus will lie to compel him to perform his duty. This is the principle upheld by this court in United States v. Black, 128 U. S. 40, and upon the authority of that case the defendant claims that no mandamus can be issued against him.

The writ was refused in the Black case, because, as the court held, the decision which was demanded from the Commissioner of Pensions required of him, in the performance of his regular duties as commissioner, the examination of several acts of Congress, their construction and the effect which the latter acts had upon the former, all of which required the exercise of judgment to such an extent as to take his decision out of the category of a mere ministerial act. A decision upon such facts, the court said, would not be controlled by mandamus. The circumstances under which a party has the right to the writ are examined in the course of the opinion, which was delivered by Mr. Justice Bradley, and many cases upon the subject are therein cited, and the result of the examination was as just stated.

In this case the facts are quite different. There is but one act of Congress to be examined, and it is specially directed to the Treasurer. We think its construction is quite plain and unmistakable. It directs the Treasurer to pay the interest on the certificates which had been redeemed by him, and the only question for him to determine was whether these certificates had been redeemed within that meaning of that act. That they were, we have already attempted to show, and the duty of the Treasurer seems to us to be at once plain, imperative, and entirely ministerial, and he should have paid the interest as directed in the statute.

This case comes within the exception stated in the Black case, that where a special statute imposes a mere ministerial duty upon an executive officer, which he neglects or refuses to perform, then mandamus lies to compel its performance; but the court will not interfere with the executive officers of

Opinion of the Court.

the Government in the exercise of their ordinary official duties, even when those duties require an interpretation of the law, the court having no appellate power for that purpose. On this last ground the court denied the writ..

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 be 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.

In this case we think the proper construction of the statute was clear, and the duty of the Treasurer to pay the money to the relator was ministerial in its nature, and should have been performed by him upon demand. The judgment of the Court of Appeals must be

Affirmed.

Statement of the Case.

BALTIMORE & POTOMAC RAILROAD COMPANY v. CUMBERLAND.

ERROR TO THE COURT OF APPEALS OF THE DISTRICT OF COLUMBIA.

No. 87. Argued December 19, 1899.- Decided February 5, 1900.

Under a regulation requiring railroad tracks running through the streets of a city to be fenced, whenever the grade is "approximately even" with the adjacent surface of the streets, it is proper for the jury to say whether a track elevated two feet two inches above the surface of the street, is within the regulation.

Where the declaration averred that there was "no light" upon the engine to indicate its approach, and the proof was that an insufficient light was carried, it was held that there was no material variance.

Where the regulation required that “a headlight, or other equivalent reflecting lantern," should be carried upon a train to indicate its approach, it is for the jury to say whether an ordinary hand-lantern is a substantial compliance with the regulation.

In determining the existence of contributory negligence, the plaintiff is not liable for faults which arise from inherent mental or physical defects, orwant of capacity to appreciate what is and what is not negligence. He is only responsible for the exercise of such faculties and capacities as he is endowed with by nature for the avoidance of danger. While under the circumstances of this case the court might have held the plaintiff liable for contributory negligence, if he had been a man of mature age and average intelligence, as he was a boy of twelve years of age, it was held that the question was properly submitted to the jury. A person crossing the track of a railroad company in the streets of a city for the more convenient performance of his duties is not ipso facto a trespasser.

THIS was an action begun in the Supreme Court of the District of Columbia by the plaintiff Cumberland, suing by his next friend, against the Baltimore and Potomac Railroad Company, to recover damages for personal injuries inflicted upon him by the alleged negligence of the defendant company.

The undisputed facts were that the plaintiff, who was twelve years and four months of age at the time of the accident, was a street lamplighter by occupation, and for more than a year prior thereto had been engaged, under his father's direction,

Statement of the Case.

in lighting street lamps in the vicinity of the company's tracks on Maryland avenue in the city of Washington.

The accident occurred about dark on the evening of December 10, 1894. The weather was misty, according to some of the witnesses; rainy, foggy and very cold, according to others. The plaintiff, having lighted a lamp on the south side of Maryland avenue, between Thirteenth-and-a-half and Fourteenth streets, started across Maryland avenue and the tracks of the company, for the purpose of lighting a lamp directly opposite on the north side of the street. There was a curve in the tracks at this point, made by a turn in the railroad from Long Bridge into Maryland avenue. There was no crossing for persons or vehicles between Thirteenth-and-a-half and Fourteenth streets, and the street on either side of the right of way was separated therefrom by curbs which projected eight inches above the adjacent roadway. These curbs were about five feet from the outer rails on either side, and the tracks were carried upon ties, elevated about eighteen inches above the level of the curbs and about two feet higher than the surface of the street. The plaintiff, having lighted a lamp on the south side, started across the street; mounted the elevated roadway, in front of a train coming up from Long Bridge with the tender ahead of the engine, and just as he stepped upon the track, was struck by the tender, knocked down and run over. There was a hand signal lantern swung on the advancing end of the tender, and at the time of the accident it appeared to have been burning.

At this part of the avenue there are four or five railway tracks-two main tracks on the north side, used for passenger trains; a third to the south of these two, used for freight trains, which was the one on which the accident occurred; south of that a track diverging eastwardly into the freight station of the Richmond and Danville Railroad Company to the south of the avenue; and still further south, and south even of the gas lamp which the boy had lit, a switch diverging from the east into a private coal yard. About the place of the accident, and thence westward towards Fourteenth street, the tracks begin a curve so as to reach the Long Bridge

Statement of the Case.

at the foot of that street, and to the south, upon the inner side of this curve and about the line of Fourteenth street, there was a switchman's box, which to some slight extent obstructed the view from the east of trains coming to the avenue from the bridge.

As the boy had passed or was passing the Richmond and Danville track, and was approaching the freight track, his attention was directed to a passenger train going out on the northernmost track towards the bridge. When this had passed he proceeded on his way across, and having stepped on the freight track, he was struck, knocked down and injured by the tender attached to an engine drawing the work train, which he states he had not seen, although he testifies that he had looked in that direction, had listened for approaching trains, and had neither seen nor heard any.

The engineer testified that, when he was between Fourteenth street and the place where the accident happened, he saw the form of a person moving at a brisk walk in the direction of the tracks, about fifteen feet away from them and about fifty or sixty feet in front of the train. He could not tell whether it was a man or boy. When in the neighborhood of thirty feet away, he saw he was coming so near the track that he thought probably he was going to walk on it. He then reversed the engine, applied the brake to stop, and the train was brought to a standstill within the distance of eighty or ninety feet.

The fireman testified that when he first saw the boy he was approaching the track at a brisk walk, and was about fifteen or twenty feet from it, making his way north. He appeared to be looking across towards the moving train on the southbound main track. He was carrying some object (a ladder). He saw him put his foot on the end of the ties, and he (witness) called the engineer's attention by "hollering."

The defence rested chiefly upon the contributory negligence of the plaintiff in crossing the track at this point without sufficient care in looking out for the approach of trains.

The trial resulted in a verdict for the plaintiff in the sum of $8000, upon which judgment was entered. The case was car