113 U. S. 550; Phoenix Mutual Life Insurance Co. v. Bailey, 13 Wall. 616; New York Guaranty Co. v. Memphis Water Co., 107 U. S. 205.

It appears from the bill in this case that the plaintiff is seeking to restrain the defendant from proceeding with an action at law in the Idaho state court, brought to recover a certain sum alleged to be due as a license fee under the ordinance of June 7, 1906. In such a case a Circuit Court of the United States will not interfere to enjoin a pending suit at law. Hapgood v. Hewitt, 119 U. S. 234; Buzard et al. v. Houston, 119 U. S. 351. See also 1' High on Injunctions (3d Ed.), §§ 89-93.

MR. JUSTICE MOODY delivered the opinion of the court.

The appellant, a West Virginia corporation, brought in the Circuit Court of the United States for the District of Idaho, this bill in equity against Boise City, a municipal corporation. There was a demurrer to the bill, which, upon consideration of the merits of the case set forth therein, was sustained by the judge of the Circuit Court and the bill dismissed. The company appealed directly to this court. The facts set forth in the bill and exhibits, and the relief and grounds of relief claimed, so far as necessary to develop the point decided, may conveniently be stated in narrative form.

The company was incorporated for and is engaged in supplying the city and its inhabitants with water for municipal and domestic purposes. It had acquired the property, franchises, rights and privileges of certain individuals and corporations, who had been, from time to time, granted by ordinance of the city the privilege of laying and maintaining pipes in the streets and supplying through them water for municipal and domestic uses. The company conducted its business by virtue of these ordinances, and has invested large sums of money. The ordinances need not be set forth in detail, and it is enough to say that the company contends that they are franchises for a term of not less than fifty years, and constitute a contract incon

sistent with the license fee or tax hereafter referred to, while the city contends that they are mere permissions, revocable at any time. The rates are fixed by commissioners, acting under the authority of a law of the State, and are to remain in force three years from the date of their establishment. After the fixing of the rates and before the expiration of the three years, on the thirty-first day of May, 1906, the city enacted an ordinance requiring that the company "hereafter pay to said Boise City, on the first day of each and every month, a monthly license of $300, for the privilege granted to lay and repair water pipes in the streets and alleys of said city." The ordinance then made a demand for the monthly payment of said license, and directed the city clerk to notify the company of the requirements of the ordinance.

The main object of the bill is to obtain an injunction against the enforcement of this ordinance, upon the grounds: (1) that other corporations, associations and individuals using the streets and alleys of the city for various purposes are not required to pay a license, and therefore there was, by the ordinance, a denial of the equal protection of the laws; (2) that the city, in pursuance of its claim that the ordinances grant only a revocable permission to occupy the streets, threatens and intends to impose further burdens and assessments, and threatens to remove the pipes and the works from the city; (3) that the city has presented monthly bills and has brought an action at law in the state court to recover the amount alleged to be due on account of the license fee imposed, and that there is therefore danger of a multiplicity of suits; (4) that the ordinance has cast a cloud upon the company's franchises and right to supply water to the city and its inhabitants, and thereby depreciated the value of the company's property, impaired its credit, embarrassed its business and confiscated its property; (5) that the ordinance impairs the obligation of the contract made by the ordinances granting the rights, privileges and franchises; (6) that the enforcement of the ordinance would deprive the company of its property without due process of law and abridge its privileges

and immunities granted by the Fourteenth Amendment; (7) and that the ordinance violates the constitution and laws of the State.

A subordinate object of the bill is to recover from the city certain amounts due on account of water supplied to fire hydrants, which the city declines to pay, disputing its liability so to do.

The decree of the court below, dismissing the bill, proceeded upon a consideration of the merits of the controversy between the parties. We do not enter upon that subject, because there is a deeper question which seems to us decisive of the case. That question is whether the plaintiff is entitled, on the allegations of its bill, to relief in equity in the Federal courts.

It is obvious that the rights of which the company seeks to avail itself are rights cognizable in a court of law, and not rights created only by the principles of equity. The sum of the company's contentions is that the imposition of the license fee was illegal, unconstitutional, and void. All these contentions are open in a court of law. It is a guiding rule in equity that in such a case it will not interpose where there is a plain, adequate and complete remedy at law. This rule at an early date was crystallized into statute form by the sixteenth section of the Judiciary Act (Revised Statutes, § 723), which, if it has no other effect, emphasizes the rule and presses it upon the attention of courts. New York &c. Co. v. Memphis Water Co., 107 U. S. 205, 214. It is so well settled and has so often been acted upon that no authority need be cited in its support, though it must not be forgotten that the legal remedy must be as coinplete, practicable and efficient as that which equity could afford. Walla Walla v. Walla Walla Water Co., 172 U. S. 1, 11.

A notable application of the rule in the courts of the United States has been to cases where a demand has been made to enjoin the collection of taxes or other impositions made by stre authority, upon the ground that they are illegal or unconsti tional. The decisions of the state courts in cases of this kod are in conflict, and we need not examine them. It is a m matter of choice of convenient remedy for a State to perron

its courts to enjoin the collection of a state tax, because it is illegal or unconstitutional. Very different considerations arise where courts of a different, though paramount, sovereignty interpose in the same manner and for the same reasons. An examination of the decisions of this court shows that a proper reluctance to interfere by prevention with the fiscal operations of the state governments has caused it to refrain from so doing in all cases where the Federal rights of the persons could otherwise be preserved unimpaired. It has been held uniformly that the illegality or unconstitutionality of a state or municipal tax or imposition is not of itself a ground for equitable relief in the courts of the United States. In such a case the aggrieved party is left to his remedy at law, when that remedy is as complete, practicable and efficient as the remedy in equity. And the rule applies as well where the right asserted is by way of defense. Insurance Co. v. Bailey, 13 Wall. 616, 623.

In order to give equity jurisdiction there must be shown, in addition to the illegality or unconstitutionality of the tax or imposition, other circumstances bringing the case under some recognized head of equity jurisdiction, before the remedy by injunction can be awarded. The leading case on the subject is Dows v. Chicago, 11 Wall. 108. In that case the plaintiff sought to enjoin the collection of a tax levied upon shares of the capital stock of a national bank on the ground that the levy was unconstitutional under the state law, and that the property was not within the jurisdiction of the State. This court declined to pass upon the validity of the tax, saying, through Mr. Justice Field (p. 109):

"The illegality of the tax and the threatened sale of shares for its payment constitute of themselves alone no ground for such interposition. There must be some special circumstances attending a threatened injury of this kind, distinguishing it from a common trespass, and bringing the case under some recognized head of equity jurisdiction before the preventive remedy of injunction can be invoked. It is upon taxation that the several States chiefly rely to obtain the means to carry on

their respective governments, and it is of the utmost importance to all of them that the modes adopted to enforce the taxes levied should be interfered with as little as possible.

"No Court of equity will, therefore, allow its injunction to issue to restrain their action, except where it may be necessary to protect the rights of the citizen whose property is taxed, and he has no adequate remedy by the ordinary processes of the law. It must appear that the enforcement of the tax would lead to a multiplicity of suits, or produce irreparable injury, or, where the property is real estate, throw a cloud upon the title of the complainant, before the aid of a Court of equity can be invoked."

This case has been frequently followed and its governing principle never doubted. Hannewinkle v. Georgetown, 15 Wall. 547; State Railroad Tax Cases, 92 U. S. 575, 613; Union Pacific Railway Co. v. Cheyenne, 113 U. S. 516, 525, 526; Milwaukee v. Koeffler, 116 U. S. 219; Pittsburgh &c. Ry. Co. v. Board of Pub. Works, 172 U. S. 32; Arkansas Building &c. Association v. Madden, 175 U. S. 269.

In the case last dited, Mr Chief Justice Fuller made the following important observation (p. 274):

It is quite possible that in cases of this sort the validity of a law may be more conveniently tested, by the party denying it, by a bill in equity than by an action at law; but considerations of that character, while they may explain, do not justify, resort to that mode of proceeding."

In Shelton v. Platt, 139 U. S. 591, a bill was filed in the Circuit Court of the United States to restrain the collection of a license tax imposed by the State of Tennessee on the United States Express Company, upon the ground that it was unconstitutional. The bill alleged that the property of the company was employed in interstate commerce and was necessary to the conduct of it, and that if it were seized by the sheriff it would greatly embarrass the company in the conduct of its interstate business, subject it to heavy damage and the public to great