Dixon, C. J.
Notwithstanding the ambiguity of the act, arising out of the obscure and inconsistent provisions of the second and third sections, the intention of the legislature not to-authorize the district board to contract for and pay a greater sum than $800, without the assent of a majority of the qualified voters of the district, to be expressed by a vote at a special or annual meeting, is very plain. This appears from the first section. The contract set out in the complaint is for the-*520payment of $1050; and it is averred that it was entered into by the board without the assent of the qualified voters, or a majority of them, given or obtained at any special or annual meeting, for the payment of the additional $250, as provided for in section one. In this the board clearly exceeded their powers, and the contract is for that reason void. There can be no doubt, in such a case, that the tax-payer may have his remedy by injunction to restrain_ the collection of taxes assessed, or supposed to have been assessed, for the purpose of giving effect to such void contract; but whether, after the supposed assessment, and after the warrant for the collection of the illegal taxes has been issued, two or more can join in an action to obtain such relief, is not a question necessarily involved in this case. For, assuming that they cannot, and that the objection of an excess of parties plaintiff may be raised by demurrer in this form, concerning which there is some conflict of opinion in New York (see Walroth v. Handy, 24 How. Pr. R., 353), still we are of opinion that this complaint presents a cause of action in which all the plaintiffs have a common interest, and for the prosecution of which they may properly join in one action. The relief demanded consists in part in having the contract entered into by the district board declared void, as well as in restraining the collection of the illegal taxes. So far as the former cause of action is concerned, that is, the annulling of the contract, the plaintiffs have properly joined, and therefore the demurrer should be overruled. But as this cause of action cannot be adjudicated in the absence of Yost, the other party to the contract, who is the person chiefly interested in sustaining the contract as against the plaintiffs, and not a party to this suit, we think the court below erred in directing final judgment for the plaintiffs. The demurrer should have been overruled, and an order entered requiring the plaintiffs to bring in Yost as a party defendant to the action. We must therefore *521reverse so much of the order as directs judgment in favor of the plaintiffs, and remand the cause with directions as above stated.
By the Court — Ordered accordingly.
On a motion for a rehearing, the attorneys for the appellants argued that the object of the suit was to restrain the collection of a tax out of personal property, and to have the act of the legislature above cited, and the agreement between the district and Yost, declared void. 1. Courts will not restrain the sale of personal property for taxes, both on grounds of public policy, and because there is an adequate remedy at law. 2. The complaint assumes that the act and contract are void on their face. If this be true, all proceedings by the board under them are void, and plaintiffs have a legal remedy. An equitable action cannot be maintained for setting aside either an act of the legislature or an instrument void upon its face. Scott v. Onderdonk, 14 N. Y., 9; 2 Coms., 118; 26 Wend., 132; 9 Paige, 388; 16 Wis., 269.—The respondents’ counsel cited in reply to the latter point, Story’s Eq. Jur., §§ 688-700, and notes; Pierce on Am. R. R. Law, 400, 508; Dodge v. Woolsey, 18 How. (U. S.), 331, 341; Manderson v. Commercial Bank, 28 Pa. St., 379.
Dixon, C. J.
The property of the plaintiffs, seized by the treasurer of the district, and which he was about to sell at public auction to satisfy the taxes, was personal, and part of the relief demanded by the complaint consisted in restraining such sale. It is the settled rule in this court, that equity will not interfere by injunction to prevent the sale of personal property for the non-payment of a tax, where the illegality of the tax is the sole ground of complaint. Van Cott v. Supervisors Milwaukee County, 18 Wis., 247; Chicago and Northwestern R. R. Co. v. Borough of Fort Howard, ante, p. 44. We were in doubt as to how far this rule might have been overlooked or contravened in the former decision; and hence a rehearing was or*522dered, and the cause re-argued at this term by direction of the court, upon that point. Further argument and investigation have convinced us that our first decision was correct, and should stand as the law of the case. The ground on which equity refuses to take cognizance of and proceed in such cases, namely, that the plaintiff has an adequate remedy at law, is in no proper sense jurisdictional. The court has power to hear and determine the action, and in general will do so, unless objection in proper form be taken. This may be by demurrer to the complaint, when the objection appears upon the face of it; otherwise by answer. If not taken in one or the other of these forms, it is waived. Tenney v. State Bank of Wisconsin, 20 Wis., 152, and authorities there cited; Grandin v. Le Roy, 2 Paige, 509. This shows that it is not a question of the jurisdiction of the court over the subject matter of the action; for where that is wanting, it is well known that no consent or waiver of objection by the parties will confer it. Such an objection is never waived, but may be taken at any time, either on appeal or when the question of jurisdiction is collaterally involved. The objection that the plaintiff has an adequate remedy at law is no more than a rule of practice in the court of chancery, upon which the action will be dismissed if the attention of the court is called to it at the proper time and in the proper manner; and although it is most frequently spoken of by courts and writers as a question of jurisdiction, it is strictly inaccurate to call it so. There is no want of jurisdiction, and should the court erroneously proceed, after objection properly taken, according to its own rule, it is very clear that the judgment would not be void. It might be erroneous, and subject to reversal in a direct proceeding, but it could not be collaterally impeached or disregarded. The defendants do not make this a distinct ground of demurrer. They demur only on the ground that the complaint does not state facts sufficient to constitute a cause of action. Hence the objection that the plaint*523iffs have an adequate remedy at law is not raised, and is not before us to be considered. Burhop v. The City of Milwaukee, 18 Wis., 431; Van Cott v. Supervisors of Milwaukee County, supra. This alone is a sufficient answer to the question, and shows that there was no error in the former judgment.
But there is another and, as it seems to us, more satisfactory reason why the remedy by injunction should prevail in this case. The action is not instituted merely for the purpose of preventing the sale of personal property for taxes illegally assessed, which may be amply redressed by a suit at law. The principal object of the action is, to annul an unauthorized contract entered into by the district board. Upon the facts stated, there can be no doubt of the fraudulent nature of the contract, or that a court of equity will set it aside at the suit of the tax-payers of the district. The taxes are levied for the purpose of carrying that contract into effect. We are of opinion that the collection of the taxes in such a ease may be stayed by injunction as a proper subsidiary ground of relief, upon the principle that the jurisdiction of the court having once rightfully attached, it shall be made effectual for all the purposes of complete relief. The court will not annul the contract and at the same time permit the officers of the district to collect the taxes, to be afterwards recovered back by a multiplicity of suits at law. It will not, when it can determine the matter, “ he a handmaid to the other courts ; nor beget a suit to be ended elsewhere.”
By the Court — TRe former judgment of this court is re-affirmed, and the cause remanded as therein directed.