dissenting:
Demands upon my time permit only a brief statement of the reasons why I cannot yield my assent to the judgment awarding the writ of mandamus in this case.
I am not unmindful of the weight that ought to be given, not only by the courts but by the succeeding heads of executive departments, to the long-continued practice of a department involving the interpretation of a law prescribing its regularly recurring duties in respect of the administration of an agency intrusted to it. But that the head of such a department has the right, in his own administration, to reverse the practice of his predecessors whenever, in his judgment, that practice has not been founded on a correct interpretation •of the law, I have no doubt.
Save as to a subject-matter _ finally closed and settled under the former practice, and which thereby takes on the nature of a vested right of property, the rulings on which that practice is founded contain no element of estoppel or res judicata as the doctrines thereof are applicable in judicial proceedings.
It is proper to say here, however, that this proposition is not denied in the opinion of my brethren.
I agree that where the law directs the performance of a •specific act, the facts of which are plain, the executive officer cannot escape the obligation by raising a question of construction merely: his duty does not cease to be ministerial because, to some slight extent, he must give interpretation to the law. This is what I understand to be the salutary doctrine enounced in Roberts v. U. S., 176 U. S. 221; S. C., Roberts v. Valentine, 13 App. D. C. 38.
But when the ruling of the departmental chief does not involve a mere question of obedience to a law commanding in reasonably plain terms a duty to be performed in a particular case, and necessarily requires investigation of the special facts relating to each particular case that shall be presented for the application of a law couched in general terms, a very different condition arises.
*604A discretionary duty is then imposed, and its exercise is not subject to judicial control: it is only politically examinable and parties aggrieved must look to tbe legislative branch for relief.
I do not consider that Ave are called upon, in this case, to determine Avhether tbe item of tbe new regulation relating to mail matter of tbe second class, is narrower than tbe terms of tbe statutes justify; because tbe Postmaster-General, on tbe appeal from tbe decision of bis assistant, based bis decision, not upon tbe regulation as expressing tbe entire meaning of tbe law, but upon tbe broad ground that tbe facts showing tbe nature, purposes, ■ and manner of publication of relator’s alleged periodical did not bring it witbin tbe privilege of tbe law. In my opinion, tbe duty of determining Avbetber tbe railway guide was, under all these facts, a periodical publication of tbe second class as defined in sections 12 and 14, or one of tbe third class as defined in section II of the statute, was not ministerial simply, but quasi judicial.
Tbe Congress did not deem it advisable to admit all of tbe periodical publications of tbe country to tbe second-class mail privilege. On tbe other band it did not define with perfect precision tbe line of separation between those admitted and those excluded. When, therefore, a new publication is presented for carriage at second-class rates, tbe Postmaster-General is bound to make inquiry and pass upon tbe right. This necessarily involves tbe exercise of discretion.
Were it in our power to review bis decision in tbe present case, I would not be prepared to say that it was erroneous — at least not clearly so.
There are two general kinds of periodicals mentioned in tbe statutes; one belongs to tbe second class, tbe other to tbe third.
Tbe railway guide is not necessarily a periodical of tbe second class, although it conforms to tbe conditions of tbe first, second, and third clauses of section 14. Coming tben to tbe fourth clause, though it has a legitimate subscription list it is not “ devoted to literature, tbe sciences, arts, or some special industry.” Its claim depends, tben, upon whether it “be originated and published for tbe dissemination of *605information of a public character.” It does contain information for those who travel beyond the limits of local transportation lines; but whether this limited use by only a part of the public, and a relatively small part, answers the requirement of the statute is a subject of grave doubt, to say the least.
Granting the value of the book — for such it practically is — as one of reference for those engaged in general or distant travel, it must nevertheless be borne in mind that the succeeding numbers published and mailed, do not, like the ordinary periodical of subscription issue, consist of entirely new matter for the information of the public.
The great bulk of the matter carried from date to date of successive issue is old. Most of it has been carried time and again and delivered to the Same subscribers; for all that the later issue undertakes to do is to note such changes in schedules, or such new ones as may have occurred since the next preceding issue.
Without pursuing the subject further, I am of the opinion that the judgment should be reversed and the petition dismissed.
A writ of error to the Supreme Court of the United States was prayed and allowed.