NORTONI, J.
(after stating the facts). — It is argued that the petition fails to disclose the contract relied upon therein was within the powers of the municipal corporation. We are admonished by a great jurist that in determining the extent of the power of a municipal corporation to make contracts and in ascertaining the mode in which such power is to be exercised, careful attention should be given to the charter provisions of the municipality and the general legislation of the state on the subject, if there be any. And, it is said where there are express provisions on the subject those will, of course, measure the authority of the corporation as far as they extend. [1 Dillon on Municipal Corporations (4 Ed.), sec. 443.] After looking into the matter, it is ascertained that section 48 of article 4 of the State Constitution provides “The General Assembly shall have no power to grant, or to authorize any .... municipal authority to . . . . pay nor authorize the payment of' any claim hereafter created against the State, or any county or municipality of the State, under any agreement . . . made without express authority of law; and all such unauthorized agreements or contracts shall be null and void.” The inhibition of the constitutional provision is obviously leveled against the power of municipalities to either pay or authorize the payment of moneys on contracts made without express authority of law and it says, too, that contracts made without such express authority shall be null and void. Accepting the allegations of the petition as true, it appears the defendant, Kirkwood, is a city of the fourth class organized and existing under the general laws of this State to be found in article 5, chapter 91, *611Revised Statutes of Missouri 1899 as amended. See also article 5, chapter 91, Ann. St. 1906. In these provisions may he found the charter powers of the city. Among other powers therein conferred upon the mayor and hoard of aldermen is one to employ counsel to represent the city in certain cases. [Section 5907, R. S. 1899, as amended in 1903.] See Laws of Missouri, 1903, page 81, Ann. St. 1906, sec. 5907. This statute provides “if deemed for the best interests of the city, the mayor and board of aldermen may by ordinance employ special counsel to represent the city either in a case of vacancy in the office of city attorney or to assist the city attorney and pay reasonable compensation therefor.” The plaintiff relies upon this statutory provision for express authority authorizing the city to enter into the contract with him declared upon in the petition. It is urged on behalf of the city that even though this statute confers authority upon the mayor and hoard of aldermen to employ special counsel by ordinance, the petition is fatally defective in that it fails to allege there was either a vacancy in the office of city attorney at the time the contract was made or that the plaintiff was employed to assist the city attorney as mentioned in the statute. We are not impressed with this argument, for if the petition is otherwise sufficient, and nothing appears to the contrary, the law will presume the city officers exercised their authority rightly; that is to say, it will he presumed either that there was a vacancy in the office of city attorney or that the plaintiff was employed to assist such city attorney if the city had such an officer. Even in cases of municipalities and tribunals of limited authority, when it appears they are acting on a given matter within their jurisdiction, the presumption of right and not of wrong attends their official acts unless the contrary appears. [Rutherford v. Hamilton, 97 Mo. 543,11 S. W. 249; Aurora Water Co. v. Aurora, 129 Mo. 540, 31 S. W. 946; Asphalt Paving Co. *612v. Ullman, 137 Mo. 543, 38 S. W. 458; State to use v. Crumb, 157 Mo. 545, 57 S. W. 1030.]
It is argued that though the petition charges the city duly passed an ordinance, which, of course, includes the action of the mayor and the board of aider-men, authorizing the employment of an attorney, it does not appear in the petition that such'ordinance authorized the employment of the present plaintiff in that capacity. It is said although the ordinance directed and required the defendant, city collector, Pagen-steeher, to employ counsel on the terms therein specified and that he did so, the contract so entered into by the collector was wholly, ineffective and void for the reason the legislative department of the municipality could not delegate its discretion in that behalf. This argument we accept as sound in principle for the charter provision to he found in section 5907 as amended is to the effect that the mayor and board of aldermen may by ordinance employ counsel if deemed for the best interest of the city. The matter of employing counsel to represent the municipality in matters of controversy certainly involves the exercise of discretion. As a general proposition, the discretion of municipal governments resides in the lawmaking power. In this case, the statute in plain terms lodges the discretion as to the employment of counsel with the mayor and board of aldermen to be exercised by them, “if deemed for the best interest of the city. ’ ’ And furthermore it directs that body to exercise the power conferred in the usual manner by passing an ordinance to that effect.
It is true the mayor and board of aldermen did pass an ordinance which directed the collector to employ counsel, but so far as the allegations' of the petition disclose, the matter of discretion as to what particular counsel should be employed was attempted to be delegated to the collector, for it is not averred that the collector was directed by ordinance to employ the *613plaintiff. Had the ordinance directed the collector to employ plaintiff on the terms specified, the contract thereafter made by the collector with plaintiff in accordance with the brdinance would be entirely validl In such circumstances, the discretion as to the particular counsel to be employed would have been exercised by the proper authority and the act of entering into the contract by the collector would have been ministerial in character only. It is always competent for a municipality to delegate to an agent the execution of a mere ministerial act unless restrained by express provisions to the contrary. [Ruggles v. Collier, 43 Mo. 352; Hannibal & St. Jo. R. R. Co. v. Marion Co., 36 Mo. 294; 1 Dillon on Municipal Corporations (4 Ed.), sec. 96; 20 Am. and Eng. Ency. Law (2 Ed.), 1218.]' But when the grant of power is to the mayor and board of aldermen to act upon a given subject if deemed for the best interest of the city, as in this case, it involves a discretion which they may not delegate to another. Such a grant involves the idea that the mayor and board of aldermen are to act as one deliberative bod?/to the end that they may assist each other by their united wisdom and experience, and the result of their conference be the ground of their determination. The discretion thus conferred upon the particular tribunal' relates not alone as to whether the best interests of the city demand) the employment of a counsel and the subsequent passage of an ordinance to that effect, if the question be determined in the affirmative, but requires as- well that they shall exercise their discretion as to who shall be so employed as such counsel. Legislative power implies judgment and discretion upon the part of those who exercise it, and a special confidence and trust upon those who confer it. The discretion thus involved, therefore, may not be delegated to another unless expressly authorized. [Ruggles v. Collier, 43 Mo. 352; St. Louis to use of Murphy v. Clemens, 43 Mo. 395; 1 Dillon on Municipal Corporations *614(4 Ed.), sec. 96; 20' Am. and Eng. Ency. Law (2 Ed.), 1217.] That discretion conferred npon one class of city officers by positive legislative direction may not he transferred or delegated to others is a proposition universally true. [Sheehan v. Gleeson, 46 Mo. 100; City of St. Louis v. Russell, 116 Mo. 248, 22 S. W. 470; East St. Louis v. Thomas, 11 Ill. App. 283; Pinney v. Brown, 60 Conn. 164; Broom’s Legal Maxims (7 Ed.), 838; Joyce on Electric Law (2 Eld.), sec. 236; Mechem’s Public Officers, sec. 567; Tiedeman on Municipal Corporations, sec. 113; Throop’s Public Officers, sec. 573; 1 Am. and Eng. Ency. Law (2 Ed.), 975, 976.]
The case of East St. Louis v. Thomas, 11 Ill. App. 283, is directly in point to the effect that the power to appoint an attorney, being vested by charter in the city council, it cannot be delegated to the mayor by ordinance or otherwise. And an ordinance providing that in certain contingencies the mayor may appoint an attorney is void.
"While the-contract with the city declared upon in the petition is void and unenforceable for the reason stated, it is not void for ultra vires. It is within the power of the municipality to make such contract for the employment of counsel as indicated by the statute referred to. In so far as the city is concerned, the contract is intra vires and its infirmity, lies only in the fact of defective execution of the power properly lodged in the mayor and board of aldermen.
Whatever may be said on the application of the doctrine of estoppel to' municipal corporations with respect to ultra vires engagements or contracts expressly prohibited by law, is irrelevant here for the reason the case presents no such question and it will not be noticed. It is certainly now well settled that the doctrine of estoppel applies with full force to municipal corporations in those cases where the contract is within the power of the corporation and is *615infirm only in the mode or manner of its execution. There is a distinction made, too, in some of the cases where the doctrine of estoppel is invoked as to contracts which had been performed in good faith hy one dealing with either a municipal or private corporation and the infirmity lies in a defect of power with respect to a matter not prohibited by law. In such cases, presenting a defect of power in the first instance; that is, where the power was not expressly conferred upon the corporation to enter into the contract and such contract was not expressly prohibited, the courts have sustained and enforced the plaintiff’s right to recover in suits on the contract hy applying the doctrine of es-toppel when to do otherwise would entail an unjust result. In those cases, it appeared the plaintiff had acted in good faith and performed his part of the engagement hy incurring expense and trouble, the fruits of which were accepted and appropriated hy the defendant corporation. See Hitchcock v. Galveston, 96 U. S. 341; State Board of Agriculture v. The Citizen’s Street R. W. Co., 47 Ind. 407. However, unless most carefully scrutinized, those cases would seem to extend the doctrine quite beyond the limits generally accepted to he sound on principle when applied to municipal corporations. [1 Dillon on Municipal Corporations (4 Ed.), 457.]
The authorities generally go to the effect that the doctrine of an equitable estoppel may not he invoked as to municipalities which have acted wholly beyond their power in entering into the contract. But it is not so where it appears as here, that the contract relied upon was one within the express powers conferred. The principle of the authorities referred to is that one cannot do indirectly, what cannot he done directly, and where there is no power or authority vested hy law in officers or agents, no void act of theirs can be cured by aid of the doctrine of estoppel. However, where the power is clearly vested in the municipality and it is *616irregularly exercised or there are defects and omissions in exercising the authority conferred by law, as in this case, which presents only the defective execution of the .power, the doctrine of equitable estop-pel, it is said, may well be applied by the courts. Indeed, it is the universal rule that as to matters within the scope of their powers and the powers of their officers such corporations may be estopped upon the same principles and under the same circumstances as natural persons. See 2 Herman on Estoppel, sec. 1222; Motz v. Detroit, 18 Mich. 496; Brown v. Bowen, 30 N. Y. 519; Moore v. The Mayor, etc., 73 N. Y. 238.
It is the doctrine, too, of our own Supreme Court that where a municipal corporation enters into a contract within its powers, the doctrine of estoppel obtains with the same force as against individuals. [Union Depot Co. v. City of St. Louis, 76 Mo. 393; Union Depot Co. v. City of St. Louis, 8 Mo. App. 412.] For an application of the same doctrine in the case of a county which had contracted within its powers but had defectively executed the power conferred, see the recent case of Simpson v. Stoddard Co., 173 Mo. 421, 463, 464, 465, 466, 73 S. W. 700.
It appears from the allegations of the petition, which stand confessed by the demurrer, that immediately upon the defective execution of the power by contracting through its collector for the services, plaintiff entered upon and discharged, in a large measure, the terms and conditions of the contract. He defended certain suits then pending and faithfully performed each and every condition of the contract on his part until prevented by the city authorities. It is averred that through his aid and assistance the city collector collected more than $10,000 of the taxes and paid them over to the city of Kirkwood and both the city and the collector have wholly failed and refused to recompense him for his services. Under these circumstances, the most elementary principles of natural justice re*617quire that plaintiff slionld be compensated for such services as lie bas rendered. By accepting the fruits of the contract and appropriating the moneys arising from the plaintiff’s efforts thereunder, the defendant city, through its voluntary act, has invoked the principle of an equitable estoppel above referred to and it may not now dispute the obligation to recompense plaintiff on the terms which induced his services. In so far as the city is concerned, the demurrer should be oyerruled.
As to the co-defendant, Pagenstecher, the city collector, we believe the demurrer was rightfully sustained, for it appears throughout the petition that he acted only in his official capacity under the ordinance requiring him to contract with an attorney, and there is not a word indicating that he intended to assume a personal obligation. In every case, the presumption. is that municipal officers act for their principal and not for themselves, unless something to the contrary appears. When such officers act within their authority, they are held to a personal obligation only in those cases where by apt and appropriate language a clear intention to assume such is disclosed. [1 Dillon (4 Ed.), sections 452, 453, 454; Mechem’s Public Officers, sec. 818.] As the powers and duties of such officers are defined and marked out by the law, they are open to ascertainment for one and all alike. In this respect, there is a distinction between a public and a private agency. In those cases, therefore, where the obligation of the public negotiated through its agent, is sought to be enforced against the municipality, the rule obtains that every person is required at his peril to ascertain at the time the contract is entered into that it is within the scope of the authority which the law conferred upon the officer. [Cheeney v. Brookfield, 60 Mo. 53; Mister v. Kansas City, 18 Mo. App. 217; Mechem’s Public Officers, sec. 829; 1 Dillon (4 Ed.), Municipal Corporations, 447.]
*618From these principles, it would seem to be just that a public officer, who avowedly contracted for the municipality only, and acted in good faith without any misrepresentation of facts, ought not to be held personally liable for a mere defective execution of the power which appears to have resulted from an error as to the law, induced by the concurrence of all parties. While there are authorities to the contrary, the rule in this State is that an officer of a municipality, contracting officially and under an innocent mistake of the law in which the other party, with equal opportunities of knowledge, participated, neither party at the time intending to affix a personal liability, will be adjudged not personally liable on the contract. [Humphrey v. Jones, 71 Mo. 62.] This rule we believe to be eminently just, and especially so in the particular instance now in judgment, for it appears here that plaintiff is a lawyer and, therefore, was possessed of as much, if not more, information touching the legality or illegality of the power being exercised by the collector in entering into the contract sued upon, than either the collector, mayor or board of aldermen. In such circumstances, the doctrine is generally accepted to be sound. See Mechem’s Public 'Officers, sec. 809; 23 Am. and Eng. Ency. Law (2 Ed.), 381 and note 4 to see. 237 of 1 Dillon on Municipal Corporations (4 Ed.). The petition failed to state a cause of action against the defendant, Pagenstecher, personally, and as to him the demurrer was properly sustained.
That the case may proceed against the city, the judgment will be reversed and the cause remanded. It is so ordered.
All concur.