The contractor may also recover payment without producing the certificate which was made a condition precedent, if the owner has waived his right to insist upon the-condition. A California case held that where a building had been completed and occupied apparently without objection from the architect or owner, although no certificates had been given, the occupancy was evidence that the owners waived the requirement of a certificate and payment was clue on the contract. In a Wisconsin case it was held that payment of 50 per cent of the price without demanding the certificate was a waiver of the certificate as to that part and also as to the other part, unless notice had been given that the certificate would be required for the remainder of the work. Of course each of these cases was determined on the special circumstances under which it arose. It is certain that occupancy alone does not necessarily constitute a waiver of the condition as to the certificate. The question of waiver of this condition is subject to the ordinary considerations of the law upon that subject.

It is generally held that if by the death of the architect it becomes impossible to procure the certificate the non-production will not prevent recovery by the contractor.

The next question that arises is as to the effect of the certificate when once given. It is not finally binding on the parties in such a manner that its findings cannot be contradicted, unless the provisions of the contract render the certificate of binding effect. As the certificate depends on the contract for its effect it can have force only to the extent therein provided for, and a certificate pretending to settle matters not left to the architect's decision is in-effective as to such matters.

Even after a certificate has been given which according to the contract is finally binding on the parties, it may be impeached on various grounds so as not to bind the owner to pay for the work certified to. Fraud or mistake are generally grounds for avoiding it. The wilful disregard by the architect of his duty has been held a ground for avoiding the certificate; as has the concealment of defects by the builder, and collusion between the contractor and one of the parties. As to just what facts constitute a ground for disregarding the certificate, the law differs in the different states. The law in some states is that if an architect gives a certificate for work which subsequently shows imperfections which have been concealed from the architect and which he could not have discovered by the use of reasonable care in inspection, such certificate does not waive such imperfections, and the owner need not pay the full contract or certificate price for such work. The law in other states, on the other hand, is that nothing short of fraud or collusion be-tween the contractor and the architect will excuse the owner from payment according to the certificate. Some states even go so far as to say that even fraud will not excuse the owner. In such cases, however, the owner would have a claim against the architect for his loss. Of course each case depends on the wording of the contract. Where under the contract the certificate is merely an expression of the architect's opinion that the work is in compliance with the provisions of the contract, such certificate cannot be conelusive evidence of the performance of the contract. The question can arise only under contracts which provide that each party shall be bound by the certificate. Where on any ground the certificate can be disregarded, the owner is enabled to make a claim for decs fects or omissions which would be excluded were he bound by the certificate. The fact that the work certified to is not entirely completed, or that the architect has estimated the work done pursuant to the contract as less than the work actually done, or made a mere mistake or error in judgment, does not constitute fraud vitiating the certificate, or raise a valid ground for impeachment. There may therefore be negligence on the part of the architect in giving a certificate which would give rise to a right of action against him on the part of the owner, but which would not affect the binding-nature of the certificate; for the architect would be responsible to his employer for his failure to use care and skill in giving the certificate as in other parts of his work.

To resume the subjects last treated: The architect's certificate has, as between owner and contractor, whatever force is assigned to it by their contract; if they have made it merely a condition precedent to payment, then it is important only to entitle the contractor to recover, and he may even recover without it under certain circumstances varying in different jurisdictions; the certificate would have no further effect in binding the parties, and would be only prima facie evidence of the facts stated in it; it could be contradicted by the owner, if, for instance he claimed damages for defects the existence of which was inconsistent with the certificate. If, however, the parties have agreed to be bound by the certificate, then the owner could not recover in such a case unless he was prepared to show that there were grounds for disregarding the certificate, as above stated.

A question might arise as to an architect's power to withdraw or to alter a certificate once given. If there were such cause as would furnish ground for disregarding the certificate, such as a fraudulent concealment from the architect, clearly he should be at liberty to withdraw it. Should the architect, however, attempt to withdraw or alter a certificate merely to correct his own mistake, and should the contractor refuse to submit to the desired change, the architect would be put in an awkward position. The certificate given would be sufficient under the contract to fix the rights of the parties, and there would be no ground for setting it aside. For his own negligence he would be answerable to the owner; but there seems to be no ground on which he could insist on a return of the certificate.

Where the certificate is based on measurements, as is frequently the case with interim certificates, it would seem that the contractor has a right to be notified and to be present at the taking of such measurements even though it is not expressly provided for in the contract. As the courts are not unanimous upon the question of the necessity of such notice, it would be well, although not in all cases legally obligatory, for the architect, whenever he knows there is or may be a misunderstanding between the parties, to give them opportunity to be heard before his decision.

As to the signing of certificates where a firm of architects are employed, the signature of a certificate should of course be in the firm name. Whether one partner has power to sign is an ordinary question of the law of agency as applied to the subject of partnership. It would seem that a partner who had charge of the work undoubtedly has such authority. If the various members of the firm have participated in the work it would of course be only prudent that all should be consulted and expressly authorize the issuance of the certificate.

The subject of the architect's liability to the contractor for unjustly refusing to give a certificate is treated under the heading "Liability".