Hall, J.

The only cause of action described in the complaint is the nonperformance of the defendant’s written contract to rebuild the plaintiff’s dam. According to the defend-' ant’s promise as stated in the written instrument made a part of the complaint, he agreed to rebuild the dam which he and his sons had just constructed for the plaintiff, in the event of its being carried away within ten years. As the contract is elsewhere described in the complaint,—evidently with the purpose of stating it according to its legal effect,— the defendant promised, in case the dam should be thus carried away, to build another one, upon the same site; in a lawful and workmanlike manner.

The paragraphs of the answer which were demurred to, contain a complete defense to any claimed liability of the defendant upon a contract to rebuild the dam according to the plans and specifications upon which it was constructed by the defendant and his sons.

Section 8699 of the General Statutes is as follows: “When any person or corporation purposes constructing a dam or reservoir in a locality where the life or property of any other persons may be endangered through the insufficiency thereof, the plans and specifications for such dam or reservoir shall be submitted to any member of said board of civil engineers, who shall examine the ground where the dam or reservoir is to be built, and the plans and specifications therefor, and if he approve the same, he shall issue a certificate authorizing the construction of such dam or reservoir, and no such dam or reservoir shall be constructed without such approval and certificate.”

*211 Section 8700 provides for an inspection of the dam during its construction by the engineer under whose authority it is being built, and that such dam or reservoir shall not be used until a certificate approving of the same has been obtained from such engineer and recorded in the town clerk’s office.

Chapter 218 of the Public Acts of 1893, p. 363, imposes a penalty of $500 upon any person or corporation who shall build any dam or reservoir except in compliance with § 3699, or who shall use any dam thereafter constructed until they shall have obtained a certificate as provided in § 3700; and provides that any person constructing or using such dam or reservoir, without having complied with said sections, may be enjoined from constructing or using such dam or reservoir, and that it shall be the duty of the State’s Attorney to institute any proper action to recover such penalty, and to enjoin the construction and use of such dam or reservoir.

From the facts alleged in the answer demurred to, it not only appears that the plaintiff became liable to the payment of the penalty prescribed by the statute, by having built the original dam without complying with the statutory requirements, but that the building of the original dam, as well as its use after it was constructed, were expressly forbidden by law. It is alleged in the answer that the original dam was constructed in a locality where the lives and property of others was endangered; that the plans and specifications furnished by the plaintiff were not submitted to nor approved by a member of the board of civil engineers; and that the dam was carried away by reason of the insufficient and defective plans and materials.

If the agreement sued upon is a contract to rebuild the original dam, at the same place, in the same manner and upon the same unapproved and insufficient plans and specifications upon which the original dam was built, it is a contract to do something expressly prohibited by statute, and is for that reason void.

The fact that the defendant participated in making the illegal contract does not prevent him from pleading its ille *212 gality. Although it is the policy of the law not to interpose for the purpose of aiding either party to an illegal contract to enforce its obligations or to obtain its benefits, yet, when an action is brought upon such an agreement, either of the parties to it may plead the facts showing the true nature of the transaction, and if it appears ■ that both are in equal fault, the law will leave the parties where it finds them. Funk v. Gallivan, 49 Conn. 124, 128.

The plaintiff is not aided in his endeavor to enforce the contract to rebuild, by the fact that the illegal contract to construct the original dam has been fully performed. Although it may be necessary to refer to the first contract to determine how the second is to be performed, the latter, which is the basis of the present action, is an independent contract, and, if it is an agreement to rebuild the dam as it was originally constructed, is in itself an illegal contract. It appears clearly enough from the pleadings, that the original plans and specifications were not submitted to a member of the board of civil engineers, either for the purpose of building or rebuilding the dam, and that the required approval and certificate could not be procured for the purpose of rebuilding upon the original plans after it had been proven that such plans were insufficient.

The contention that the defendant promised by the written agreement, that in case the first dam failed to stand he would build another .which should be constructed in a lawful manner, that is, upon such plans and specifications as would meet the approval of a member of the board of civil engineers, cannot be sustained. The complaint tells us that the consideration of the contract sued upon was the payment by the plaintiff of the remainder of the contract price for the building of the original dam, before inspecting the dam. Manifestly it was not the plaintiff’s purpose to.inspect the dam to ascertain whether the plans and specifications were sufficient which the plaintiff itself furnished, but to ascertain whether the defendant and his sons had performed their part of the contract. Upon the facts before us, and especially in view' of the consideration of this contract and of the *213 absence of any express provision in it that the defendant should rebuild the dam upon any other than the original plans, it would be unreasonable to interpret it as requiring him to rebuild it upon plans which might call for the expenditure of several times the amount which it cost to construct the original dam. The contract only required the plaintiff to rebuild upon the plans upon which he had built the first dam.

The court properly admitted evidence in proof of the allegations of the answer which were demurred to, and were afterwards denied by the reply; and upon the facts alleged in the answer and found proven, the defendant was entitled to a judgment upon the ground that the contract sued upon was illegal. It follows that neither the finding by the court of the facts claimed by the plaintiff not to have been properly pleaded, namely, that the plaintiff did not intend to rebuild the dam upon the old plans, and did not give the defendant an opportunity to rebuild it although he was ready and willing to do so, nor the rulings of the court admitting evidence to prove those facts, could have harmed the plaintiff.

There is no error.

In this opinion the other judges concurred.