¶1 delivered the opinion of the Court.
¶2 The appellee was indicted in the Criminal Court of Baltimore City under the Act of 1896, ch. 378, which repealed and re-enacted with amendments Art. 32 of the Code of Public General Laws of Maryland, entitled “ Dentistry.” He demurred to the indictment upon the ground that the Act is unconstitutional. The demurrer was sustained, the indictment was quashed, and the State has appealed. The Act mentioned, created a State Dental Board of Examiners consisting of six members, charged with the duty of issuing certificates to those entitled under the Act, to practice *653 dentistry in the State. The fifth and twelfth sections alone concern this appeal, and these are as follows :
¶3 Section 5. "Any person twenty-one years of age, who has graduated at, and holds a diploma from, a university or college authorized to grant diplomas in dental surgery by the laws of any one of the United States, and who is desirous of practicing dentistry in this State, may be examined by said board with reference to qualifications, and after passing an examination satisfactory to the board, his or her name, residence or place of business, shall be registered in a book kept for that purpose, and a certificate shall, be issued to such person. Any graduate of a regular college of dentistry, may, at the discretion of the examining board, be registered without being subjected to an examination.” Section 12. “ Nothing in this article shall be so construed as to interfere with the rights and privileges of resident physicians and surgeons, or with persons holding certificates duly issued to them prior to the passage of this Act; and dental students operating under the immediate supervision of their instructors in dental infirmaries or dental schools chartered by the State of Maryland.”
¶4 This Act is assailed on the ground that it violates the twenty-third article of the Maryland Declaration of Rights, and the fourteenth amendment to the Constitution of the United States. The contention is twofold. Viz :
¶5 1st. That the board may, if it chooses, refuse to examine one holding a diploma from a college or university authorized to grant diplomas in dental surgery, and can thus arbitrarily deny the right to practice dentistry in this State, to any one holding such diploma, however skilled in his profession, or however qualified to pass an examination, and that as the test of constitutionality, is, not what has been, but what may be done, or refused under the law, this grant of arbitrary power to do, or to refuse to do, must invalidate the law, and ;
¶6 2nd. That the language of the Act—“ may be examined with reference to qualifications ”—is so vague and inde *654 terminate as to permit an examination upon any subject which the whim, caprice, or hostility of the board may suggest, and thus again confers upon the board unreasonable and arbitrary power, equally fatal to the validity of the law.
¶7 If either of these contentions were well founded, we should be compelled to pronounce the law unconstitutional, because we are in hearty accord with the declarations of the Supreme Court of the United States in Yick Wo v. Hopkins, 118 U. S. 356, that “when we consider the. nature and theory of our institutions of government, the principles upon which they are supposed to rest, and review the history of their development, we are constrained to conclude that they do not mean to leave room for the play and action of purely personal and arbitrary power.”
¶8 But we cannot deduce a grant of arbitrary power from any reasonable construction of the language of this Act.
¶9 Upon the first point of tíie appellee, his position is, that as the word, “ may,” occurs twice in section five, and as there can be no question that in the later clause it is employed in its usual and natural sense, that the same sense is necessarily and unalterably impressed upon its employment in the former clause. But he has produced no authority for this position, and we do not think any satisfactory reason can be given for announcing so inexorable a rule of construction. It may indeed well be conceded, that where a word susceptible of more than one meaning is repeated in the same Act, or section of an Act, (either meaning being in each case open to reasonable adoption) a presumption arises, more or less forcible according to the circumstances, that it is used throughout in the' same sense; but where -the subject-matter to which the word refers, is not the same in both clauses, or where the surrounding circumstances are different, this presumption must yield to an adverse presumption, furnished by an analysis of the various purposes of the law, and of the language in which those purposes are expressed.
¶10 *655 Now it is too plain for controversy, that the appellee is correct in saying that the last, “ may,” is used in a permissive sense, because it is expressly coupled with “ discretion,” which negatives the possibility of its use in a mandatory sense. But if the same sense is to be impressed upon its use in the preceding clause, the result will be to nullify the law, and this result cannot be tolerated if it can be avoided by any fair and reasonable construction of the whole section. In order to reach such fair and reasonable construction let us suppose for a moment, the latter clause to be eliminated from the law. How then would the word “may,” in the former clause be understood? Would it not necessarily be construed “shall,” or “must,” in conformity with the established rule of law that where the duty to be performed, is for the benefit of the public or third persons, it shall be so construed ? The duty of examination upon application (where there is no express discretion to waive examination) is for the benefit of both the public and the applicant. For the benefit of the public, because it protects the public against ignorant and incompetent practitioners, and for the benefit of the qualified applicant, because it puts him before the public with the seal of approbation from a competent and disinterested tribunal. The origin and development of this elementary rule is clearly set forth in Sifford v. Morrison, 63 Md. 18, and many of the cases are there cited in which it has been recognised and applied.
¶11 Having determined the construction proper to be adopted if the former clause of the section stood alone, let us now restore the latter clause and see if the conclusion reached can be thereby in any manner affected. For the reason already stated, it is impossible that “may” can in the latter clause be construed “ shall,” no matter how the former “ may ” is construed, and if, merely because this cannot be done, we are compelled to construe “ may ” in the former clause as used in a permissive sense we shall be deliberately rejecting the meaning which an established *656 rule of law, and the plain purposes of the Act, require us to adopt in construing the former clause of the section. The law does not permit itself to be frightened out of its propriety by the hobgoblin of inconsistency, and we have no hesitation in holding that the only discretion conferred, is to waive an examination, when the applicant is a graduate of a regular college of dentistry and that in all other cases covered by the Act, examinations must be granted when application is made in accordance with reasonable rules as to time and place. We think the Act does mean to distinguish, for the purpose of examinations, between “a college or university authorized to grant diplomas in dental surgery,” and “a regular college of dentistry.” In the former, dentistry may be but an adjunct to the course, and there is no such assurance of thoroughness of instruction and practical application, as must be presumed in a regular dental college where the whole time of the students and instructors is given to the theory and practice of dental science. Discriminations of this character have been sustained in Williams v. Dental Examiners, 93 Tenn. 619, and in State v. Creditor, 44 Kansas 568, and the exact principle upon which these discriminations rest, has been recognized in State v. Vandersluis, 42 Minn. 129, and in numerous cases where the authority to determine what colleges are “ reputable and in good standing,” has been held not to be an arbitrary or unreasonable authority.
¶12 Upon the second point little need be said. The language of the Act might well have been more specific, but it is impossible to suppose that it refers to any other qualifications than those appropriate to and requisite for the practice of dentistry. To hold that this language would permit an examination in astronomy, classics, mathematics, or even in the kindred study of medicine, would be to adopt a forced and violent construction of the law, not for the purpose of sustaining, but defeating it.
¶13 The constitutionality of the Act was not assailed on any other grounds than those we have considered, nor can we *657 perceive how it could be otherwise successfully assailed, in view of the numerous decisions of the Supreme Court of the United States, where similar statutes have been held to violate no constitutional requirement. There is no stronger or clearer exposition of the law applicable to this case than that contained in the following passage from the much cited and oft approved case of Dent v. West Virginia, 129 U. S. 114. “The nature and extent of the qualifications required must depend primarily upon the judgment of the State as to their necessity. If they are appropriate to the calling or profession, and attainable by reasonable study or application, no objection to their validity can be raised because of their stringency or difficulty. It is only when they have no relation to such calling or profession, or are unattainable by reasonable study and application that they can operate to deprive one of his right to pursue a lawful vocation.”
¶14 In Singer v. State, 72 Md. 464, this Court in sustaining the Act of 1886, ch. 439, regulating the business of plumbers in Baltimore City, adopted the language last quoted, and added, “ no one questions the right of every person in this country to follow any legitimate business or occupation he may see fit. This is a privilege open alike-to every one. His own labor, and the right to use it as a means of livelihood, is a right as sacred, and as fully protected by the law as any other private right. But broad and comprehensive as this right may be, it is subject to the-paramount right, inherent in every government, to impose such restraint, and to provide such regulations in regard to the pursuits of life as the public welfare may require.”
¶15 The most recent expression of this Court upon this subject is in the case of the State v. Broadbelt, 89 Md. 565, sustaining the Act creating a State Live Stock Sanitary Board, from which the following passage may be appropriately reproduced. “ If the Legislature of Maryland has by the statute under consideration, made a class to which the provisions of the Act were designed to apply, and if that *658 classification is just and reasonable, and not purely arbitrary, the ruling on the demurrer (sustaining 'it) was wrong.”
¶16 The same reasons which apply to the profession of medicine, apply with equal force to the profession of dentistry, which is but a special branch of the medical profession, State v. Vanderluis, 42 Minn. 130; Gosnell v. The State, 52 Ark. 231; Louisville Co. v. L. & W. R. R. Co., 92 Ky. 233; 14 L. R. A., note, p. 581.
¶17 We were informed at the argument in this Court, that the learned Judge of the Criminal Court expressed himself as being clearly of the opinion that the statute is a valid exercise of the legislative power, and that he sustained the demurrer only on the ground that the indictment does not negative the exception contained in the 12th section of the statute, a ground not relied on by the appellee’s counsel, either below, or in this Court. The rule, that where after general words of prohibition, an exception is created in a subsequent clause or section, it must be interposed by the accused as matter of defence, is too firmly settled in this State to be questioned. Stearns v. State, 81 Md. 344; Kiefer v. State, 87 Md. 562.
¶18 For the reasons stated the judgment will be reversed, and the case will be remanded for a new trial.
¶19 Judgment reversed and nevo trial awarded, costs above and below to be paid by the appellee.