The plaintiffs bring this bill in equity for themselves and any others having a like interest who may join therein, to restrain the defendant from suspending or revoking licenses held by them for the operation of taxicabs in the city of Boston. The case comes to this court on report by the trial judge after overruling the defendant’s demurrer.
The defendant,' as police commissioner of the city of Boston, upon petition of each plaintiff, issued a license to drive a hackney carriage within the city limits, a license "to set up and use one Hackney Carriage” at a designated garage "on condition that the licensee shall comply with *275all the existing Laws and Ordinances relating to Hackney Carriages, and all rules made for the regulation of the same,” and an order designating a special stand for each hackney carriage, which order also contained the condition above quoted. While the licenses and orders were in force, the defendant notified each of the plaintiffs that his license to drive and to set up and use a hackney carriage and his license for a special stand were suspended and made inoperative from the date of the notice for the period of three days, for reasons deemed satisfactory to the defendant, namely, “For the reason that the . . . suspensions are required for the maintenance and better promotion of public convenience, in the use of the public ways, and in the operation and regulation of hackney carriages and taxis operated for hire in the City of Boston: For the reason that you have refused to comply with the authorized orders of police officers of the City of Boston, respecting and requiring compliance by you with the obligations and terms of said licenses heretofore issued to you for driving and operating hackney carriages : For the reason that you have refused and neglected to maintain service and use of ‘special stand’ assigned to you for the public convenience, and described in your said license therefor: For the reason that your refusal to observe requirements and conditions of your said licenses, and your refusal to obey lawful orders and directions of Police Officers of the City of Boston, renders you, in the judgment of the Police Commissioner, an unfit person to further exercise any privileges or benefits under authority of any of said licenses.”
Under Rule 58 of the rules and regulations of the Boston police department, the authority to issue to suitable persons licenses of the kinds above referred to and to make assignments of special stands is given to the police commissioner. Provision is also made forbidding trespassing by owners or drivers upon special stands to which they have not been assigned, and forbidding those having special stands from trespassing upon public stands. While awaiting employment by passengers, drivers are forbidden to stand their carriages in any public street or place other than at or upon a public or special stand. Every person having charge of a *276hackney carriage is required to obey the directions of any police officer respecting the standing of such carriage while waiting for passengers. The licensees are prohibited from carrying any person sick or affected with any contagious disease. It is made the duty of police officers to observe the movements of hackney carriages, especially at night, and at all times to see that the rules regulating such carriages are obeyed. In these rules and regulations the police commissioner reserves to himself the right to take away, change, modify, or reassign any and all privileges in both special and public stands at his discretion.
By St. 1909, c. 221, entitled “An Act to authorize the police commissioner of the city of Boston to revoke or to suspend licenses issued by him,” that officer was given all the powers and duties then conferred or imposed by law upon the board of police of the city of Boston, and he was specifically given all the powers of that board in respect to revoking licenses issued by him, and in addition he “may, in his discretion, for any cause deemed satisfactory to him and without a hearing, suspend and make inoperative for such period as he may deem proper any license issued by him.”
The grounds of demurrer are in part that there are no sufficient allegations in the bill to entitle the plaintiffs to relief in equity as prayed for, and that it appears from the allegations that the defendant acted within and pursuant to the power and authority conferred upon him.
The right to engage in the business of carrying people for hire upon public ways is subject to reasonable control. Commonwealth v. Gage, 114 Mass. 328, 330. Commonwealth v. Page, 155 Mass. 227. Burgess v. Mayor & Aldermen of Brockton, 235 Mass. 95. Commonwealth v. O’Neil, 233 Mass. 535, 542. See Commonwealth v. Morrison, 197 Mass. 199, 203.
The police commissioner had authority to make rules and regulations concerning this business. Commonwealth v. Gage, supra. Commonwealth v. Plaisted, 148 Mass. 375, 382. Commonwealth v. Page, supra.
The power to regulate the business gives the power to require those engaged in it to be licensed. The holder of a *277license cannot complain of limitations attaching to the privilege which, with full knowledge, he sought and accepted. McAuliffe v. Mayor & Aldermen of New Bedford, 155 Mass. 216, 220. The holder takes it subject to the right of suspension and revocation authorized by statute, Rafferty v. Police Commissioner of Boston, 259 Mass. 145, and subject to the rules and regulations and to the express conditions made a part of the license. Burgess v. Mayor & Aldermen of Brockton, supra. The cases cited support the conclusion that the right given the police commissioner to regulate and license the transportation of passengers for hire is a valid exercise of the police power and is constitutional. Licenses such as the plaintiffs have are “mere privilege]]?] or permission]]?] and in no sense a contract or property.” Burgess v. Mayor & Aldermen of Brockton, supra, page 100.
The designation of stands for carriages licensed to transport passengers for hire would be a useless ceremony unless the drivers were required to operate from the stands designated. It well may be that the distribution of such stands in different parts of the city best serves the public convenience even though in certain cases the stands prove to be unprofitable to the licensees. This method of controlling and distributing the taxicab business may have a tendency to prevent congestion in street traffic at certain points, and if the licensees conduct their business from stands assigned, the police have a better opportunity to learn whether the conveyances are used for illegal purposes and whether the conditions of the licenses are being observed. The designation of stands and the requirement that licensees maintain service at them are justified for reasons based on the public welfare and convenience. The defendant by his orders of suspension is not undertaking to control the use which may be made of the private property upon which the plaintiffs have been maintaining their stands, but only acting within the limits of his authority to control the taxicab business. The designation of stands is one of the three licenses required, and it is within the power of the defendant to suspend or revoke all licenses of the driver who refuses to occupy a designated stand.
*278The bill states that the licensees refused to occupy the special stands assigned to them and occupied with their vehicles private stands in violation of the orders of police officers acting under the direction of the police commissioner; and that such refusal was the sole and only reason for the action of the defendant, although other reasons were stated in the order. The refusal of the plaintiffs to occupy stands assigned to them was sufficient justification for the suspension of the licenses, and the action of the police commissioner based upon this refusal was not arbitrary but a reasonable exercise of his power. It is no justification for refusing to occupy the stand assigned for the licensee to offer to show that it produces little business, is unprofitable, and serves no public interest, while the private stand, which each plaintiff has chosen to occupy, is profitable and serves the public interest. The statute has clothed the defendant with power to revoke and suspend licenses issued by him, and in the assignment of stands he has the sole responsibility of deciding what the public interest requires. His conclusions in matters of fact within his jurisdiction cannot be controverted in the absence of bad faith. Tewksbury v. County Commissioners, 117 Mass. 563, 564. Filoon v. City Council of Brockton, 252 Mass. 218, 223. The Legislature evidently has considered the police commissioner a more appropriate tribunal to decide questions of fact, in matters of licenses and regulations relating to the transportation of passengers for hire upon the streets of Boston, than a court or jury. See Farmington River Water Power Co. v. County Commissioners, 112 Mass. 206, 213; French v. Jones, 191 Mass. 522, 532.
If a public officer, whether amenable to a writ of certiorari or not, is about to take action under an unconstitutional or Void statute, ordinance or regulation, in a matter which would cause irreparable injury to property rights, a bill in equity may be maintained to enjoin such action, but if the bill cannot be supported on that ground, the plaintiff is not entitled to have the question — whether his business is conducted in violation of law — decided in advance by a court of equity. Shuman v. Gilbert, 229 Mass. 225. Greene *279v. Mayor of Fitchburg, 219 Mass. 121. Commonwealth v. Norman, 249 Mass. 123, 130, 131. Davis v. Board of Registration in Medicine, 251 Mass. 283,284. For reasons already stated, the constitutionality of the statute and of the rules and regulations under which the defendant acted cannot be doubted.
The plaintiffs contend that a petition for writ of certiorari against the defendant, if an appropriate remedy, would not be adequate to enable them to raise the questions which they seek to present, because in such proceedings the return of the defendant cannot be contradicted; and they urge this as a justification for proceeding in equity. This contention cannot be maintained. Proceedings in excess of jurisdiction or on erroneous principles of law by public officers constituting quasi judicial tribunals may be corrected by petition for writ of certiorari, and, in some cases, by petition for writ of mandamus requiring them to take specific action. Money-weight Scale Co. v. McBride, 199 Mass. 503, 505. Farmington River Water Power Co. v. County Commissioners, supra, page 214. Locke v. Selectmen of Lexington, 122 Mass. 290. Warner v. Mayor of Taunton, 253 Mass. 116, 117, 118. If it be assumed that such a petition could be maintained against the defendant, the remedy thereby furnished would be adequate for the correction of errors of law. Upon such a petition the facts and rulings so far as necessary to raise the questions which the petitioners desire to have revised by the court must be stated, and “the rights of all persons have a sufficient protection, in being intrusted to public officers, clothed with important public duties, who are under oath for their faithful performance, and who cannot be supposed to have any interest or bias to misrepresent or suppress the actual facts as they took place before them.” Tewksbury v. County Commissioners, supra, page 565.
Bad faith is not charged, but it is alleged that two competing companies have been operating taxicabs from private stands precisely as the association to which the plaintiffs belong has done, and is endeavoring to do; that the defendant has taken no action to prevent the same; and that the issuing of the notices and the threats made by the defendant are *280arbitrary and capricious and, whatever their purpose, operated to prefer and benefit the two corporations as competitors of the plaintiffs at the expense of the plaintiffs and of their association, are injurious to the plaintiffs without serving any public convenience, are not authorized by law and are in violation of the rights of the plaintiffs, both under the Constitution of this Commonwealth and under the Fourteenth Amendment to the Constitution of the United States. Upon the facts alleged, for reasons already stated, it is not open to the plaintiffs to prove that the orders of the defendant, suspending the plaintiffs’ licenses for violation of the conditions upon which they were granted, caused injury to them without serving any public convenience.
The remaining question for consideration, in connection with the constitutional question sought to be raised, is, whether the alleged acts of the defendant in issuing the orders for suspension and threatening to revoke the licenses for the reasons alleged without taking action against two of their competitors, are, or could be found to be, arbitrary and capricious and an invasion of the plaintiffs’ constitutional rights. It is no defence for a person who has violated the law to show that other violations have not been prosecuted; and, upon the allegations, it does not appear that the defendant knew of the conduct of the plaintiffs’ competitors or intended by the action taken against the plaintiffs to discriminate against them or to favor their competitors, nor that he is not intending to proceed against other violators when it appears that he is justified in so doing. If he intends to enforce the conditions of the licenses he must begin with some one. The allegations would not justify the issuance of an injunction on the ground that the defendant, by his failure to proceed against other violators of the law relating to hackney carriages, had deprived the plaintiffs of the equal protection of the law under the Fourteenth Amendment to the Constitution of the United States. The discrimination against a class in the issuance of licenses as disclosed by the facts in Yick Wo v. Hopkins, 118 U. S. 356, makes that decision inapplicable to the facts stated in the plaintiffs’ bill of complaint.
*281The general allegation of arbitrary and capricious conduct states merely a legal conclusion. Silberschein v. United States, 266 U. S. 221, 225. Upon the material facts alleged, it does not appear that the acts of the defendant are or could be found to be arbitrary or capricious or that any constitutional rights of the plaintiffs have been invaded either because of the terms of the statute and rules or because of the manner in which the defendant is acting under the authority conferred upon him.
In so far as the allegations relating to the intention of the defendant to follow his order for suspension of the licenses by an order for their revocation are concerned, it is clear that equity has no jurisdiction to take from a public officer the duty of deciding questions committed to him for decision. Moneyweight Scale Co. v. McBride, 199 Mass. 503, 505.
Upon the material allegations in the bill, the defendant, in issuing his orders suspending the licenses of the plaintiffs, was acting within and pursuant to the power conferred upon him, and the plaintiffs have shown no right to equitable relief. The conclusion here reached makes it unnecessary to consider the other grounds of demurrer.
Demurrer sustained.