Opinion by
Mr. Justice Moore.1. An examination of the record discloses that the court was fully warranted in its conclusion that the common council had not acquired jurisdiction to make the improvement, and the only question presented by this appeal is whether the plaintiffs, one of whom signed the petition for the improvement, are estopped by their silence and apparent acquiescence from questioning the regularity of the proceedings. The assessment of property for a local improvement is always a proceeding in invitum, and rests upon the theory that the property of the citizen has been benefited to the extent of the amount assessed against it; but before such property can be charged with any part of the cost of the improvement, the common council must, in the manner prescribed in the city charter, acquire jurisdiction of the person and subject matter; for, without it, the right to assess such property for benefits conferred does not exist, nor should it, as a grant of such power would tend to make the common council not only the agent of the .owner, but his guardian as well. But it is contended that the plaintiffs, knowing that the improvement had been ordered, should have informed the council of the irregularity in the proceedings, and, not having done so, or made any objection to the improvement until it was completed, should now be estopped from taking advantage of these jurisdictional defects. The property owner is not the legal adviser of the common council, which usually has an attorney for this purpose. He is not required to interfere with the mode adopted to acquire jurisdiction, nor is he expected to object or protest after the proper *300initiatory steps have been taken, except to the mode or manner of the improvement, or some intermediate order or proceeding of the common council which injuriously affects his property. Jurisdiction to improve a street is obtained by the common council only in the manner prescribed in the city charter, and not by anything the property owner did or failed to do; and he is no more estopped from questioning the council’s jurisdiction upon the facts than he would be from questioning the jurisdiction of a judicial tribunal which should attempt to deprive him of his property: Canfield v. Smith, 34 Wis. 381. Objection to the jurisdiction of the person may be waived by the parties interested, but want of jurisdiction of the subject matter is never thus waived (Damp v. Town of Dane, 29 Wis. 432; In re Sharp, 56 N. Y. 257, 15 Am. Rep. 415); nor is a party who undertakes to waive it estopped from afterwards questioning the validity of the proceedings: Ruhland v. Supervisors of Hazel Green, 55 Wis. 664, 13 N. W. 877. While there is quite a conflict of opinion upon this subject, we think the trend of modern decisions, as well as the weight of authority and better reason, serves to establish the following rules as applicable thereto: (1) When, in proceedings for the levy of an assessment, the common council is without jurisdiction from the beginning, a person whose property is benefited by a local improvement is not es-topped to deny the validity of the proceedings on the ground that he made no objection thereto while the improvement was in progress: Starr v. Burlington, 45 Iowa, 87; Keese v. Denver, 10 Colo. 112, 15 Pac. 825; Coggeshall v. Des Moines, 78 Iowa, 235, 41 N. W. 617, and 42 N. W. 650; Stephan v. Daniels, 27 Ohio St. 527; Kipphart v. Pittsburgh, etc., Railway Company, 7 Ind. App. 122, 34 N. E. 375; Fayssoux v. Succession of Chaurand, 36 La. Ann. 547; Mulligan v. Smith, 59 Cal. 206. (2) But if, after jurisdiction has been acquired, the owner of property benefited by a local im*301provement, with knowledge of its progress, permitted its completion without objection, he will be estopped from questioning mere irregularities occurring in the subsequent proceedings: Elliott on Roads and Streets, 420; Wilson v. Salem, 24 Or. 504, 34 Pac. 9; Barkley v. Oregon City, 24 Or. 515, 33 Pac. 978.
2. It follows from these rules that the plaintiffs who did not sign the petition are not estopped by their silence or apparent acquiescence while the improvement of said street was in progress from questioning the void proceedings of the common council; and the plaintiff who petitioned the common council to improve the street did not thereby waive his right to have the proceedings conform to the mode prescribed in the charter: McLauren v. Grand Forks, 6 Dak. 397, 43 N. W. 710; Howell v. Tacoma, 3 Wash. 711, 20 Pac. 447, 28 Am. St. Rep. 83; Mayor v. Porter, 18 Md. 300, 79 Am. Dec. 686; Steckert v. East Saginaw, 22 Mich. 104; Tone v. Columbus, 39 Ohio St. 281, 48 Am. Rep. 438; Taylor v. Burnap, 39 Mich. 739; In re Sharp, 56 N. Y. 257, 15 Am. Rep. 415; and therefore he is not estopped to question them. His petition, fairly construed, meant that the common council should proceed to the improvement of said street in the manner authorized by law, and he never consented to the improvement being made in any other mode. The common council not having acquired jurisdiction to make said improvement, the plaintiffs have a right to challenge the validity of its proceedings, and it follows that the decree of the court below must be reversed, and one here entered canceling the assessment, and perpetually enjoining the chief of police of the City of Portland irom selling the property of the plaintiffs described in the complaint on account of said void assessment.
Reversed.