MEYER, J.

A mortgagor, who has given an estoppel certificate stating that there are no defenses or offsets to the mortgage or to the bond which the mortgage secures, will be estopped from asserting the defense of criminal usury unless it be shown that (1) the mortgagor executed the estoppel certificate under duress or other basis for invalidation, or (2) the assignee took with knowledge of the criminally usurious nature of the transaction or of the fact that duress (or other invalidating circumstances) was exerted in obtaining execution of the estoppel certificate. The papers on the motion and cross motion in the foreclosure action which is the subject of this appeal having raised issues of fact concerning whether the transaction was criminally usurious, concerning what, if anything, the assignees were aware of with respect to the nature of the transaction and concerning duress, it was error for the Appellate Division, in reversing Special Term's denial of the defendant mortgagor's motion to amend to allege criminal usury and grant of the assignees' cross motion for summary judgment, to grant to defendant summary judgment declaring the mortgage void as a matter of law and dismissing the complaint. The order of the Appellate Division should, therefore, be modified to delete so much thereof as grants judgment to defendant declaring the mortgage void and dismissing the complaint, and to remit the matter to Supreme Court, Suffolk County, for further proceedings, and, as so modified, should be affirmed, with costs.

I

In 1974, the Foursome Inn Corp., owner of the Surf and Sand Inn, in Montauk, New York, borrowed $35,000 from Broadhollow Funding Corporation secured by a mortgage on the inn premises. The mortgage was for a three-year term at an interest rate of 24% per annum and contained a provision that the mortgage principal and interest "shall become due at the option of the mortgagee * * * after default *** in furnishing a statement of the amount due on the mortgage and whether any offsets or defenses exist against the mortgage debt." Only $32,900 was paid at closing to Foursome or for closing costs, however, the remaining $2,100 having been paid to Ira S. Schwartz, then secretary-treasurer of Broadhollow.

At Schwartz' examination before trial, conducted at Foursome's instance and a copy of which was annexed to Foursome's moving papers on the first motion hereafter referred to, he testified that he was a licensed real estate broker, that the mortgage lender was in fact Stallone Enterprises Corporation (SECO) though the mortgage was taken in Broadhollow's name because of marital problems of SECO's owner, that the $2,100 represented a 6% commission to Schwartz pursuant to a commission agreement with Foursome, and that Broadhollow serviced the mortgage for SECO before its assignment to plaintiffs and continued to do so for plaintiffs after that assignment.

The assignment to plaintiffs was made in October, 1975, 10 days after Beatrice Reilly, the president of Foursome, executed on its behalf an estoppel certificate stating that "there are no defenses or offsets to said mortgage, nor to the bond which it secures." Negotiations with Mrs. Reilly for the certificate were engaged in by both Ira Schwartz and his father, Abraham, then president of Broadhollow. Mrs. Reilly's affidavit, submitted in support of the third motion by defendant hereafter referred to, sets forth facts concerning both threats to foreclose and cajoling by the Schwartzes which suggest that she may have been misled concerning the nature of her default, the offer of a proposed extension of the mortgage, or both.

In July, 1976, Foursome defaulted on its payments. Plaintiffs then declared the entire principal balance due and instituted this foreclosure action. Foursome's answer was no more than a general denial but, subsequently, it moved for leave to amend the answer to assert the affirmative defense of criminal usury. As already noted, its moving papers on that motion included a copy of Ira Schwartz' deposition. Plaintiffs, relying on the estoppel certificate, cross-moved for summary judgment. Special Term denied the motion to amend and granted plaintiffs' cross motion for summary judgment, holding the defense not available to Foursome because waived by its execution of the estoppel certificate delivered to plaintiffs. On motion for reargument Special Term adhered to that ruling. A referee to compute was then appointed and after receipt of his report judgment of foreclosure and sale was entered. On the eve of sale, however, defendant having obtained additional counsel moved to vacate the judgment on papers, including the affidavit of Mrs. Reilly above referred to, which reiterated the criminal usury involved and set forth facts suggesting, as above noted, that she signed the estoppel certificate as a result of threats or of being misled, or both. That motion, too, was denied.

On appeal to the Appellate Division that court reversed, on the law, the orders denying the motions to amend the answer and to vacate the judgment, granted both motions, denied plaintiffs' motion for summary judgment and, acting pursuant to CPLR 3212 (subd [b]), granted Foursome summary judgment declaring the mortgage void and dismissing the complaint. It reasoned that the societal interests protected by the public policy declared in the criminal usury statute could not be affected by estoppel based on conduct of the parties to the mortgage and, therefore, did not reach the question of duress. We conclude that (1) an estoppel certificate may waive criminal as well as civil usury; (2) duress, other invalidating circumstances, or knowledge on the part of the assignee before he takes the assignment of the criminal nature of the transaction or of the exertion of duress may, however, invalidate or negate the estoppel certificate; and (3) there are in the instant case issues of fact which cannot be resolved on motion for summary judgment. We, therefore, modify as above indicated.

II

Though he be a bona fide holder, an assignee of a nonnegotiable bond and mortgage takes subject to any defense that would have prevailed against his assignor (Beck v Sheldon, 259 N.Y. 208, 211; Kommel v Herb-Gner Constr. Co., 256 N.Y. 333, 336). The rule is different, however, when the mortgagor gives the assignee an estoppel certificate (Riggs v Purssell, 89 N.Y. 608, 610; see Real Property Law, § 254, subds 2, 7) or with notice of his rights and of the facts "does what amounts to a recognition or adoption" of the transaction "although it was originally void or voidable" (Rothschild v Title Guar. Trust Co., 204 N.Y. 458, 464; Ann., 110 ALR 451, 452, 457). The assignee's right of recovery does not depend upon the title or interest of his assignor, but upon the mortgagor's representation by his certificate or by his conduct that the mortgage is valid and existing (Miller v Zeimer, 111 N.Y. 441, 444; Weyh v Boylan, 85 N.Y. 394, 397; Payne v Burnham, 62 N.Y. 69, 72; see Union Dime Sav. Inst. of City of N.Y. v Wilmot, 94 N.Y. 221; Ann., 165 ALR 626, 717).

The basis for the latter rule is, of course, the doctrine of estoppel in pais (Payne v Burnham, supra, at p 73; Ferguson v Hamilton, 35 Barb 427, 437). It turns not upon any view of the negotiability of the certificate (Weyh v Boylan, supra, at p 399) or the validity of the mortgage (Valentine v Lunt, 115 N.Y. 496, 504), but upon the fact that the mortgagor would, if allowed to urge the defense, "obtain an unconscientious advantage at the expense of an innocent person" (Weyh v Boylan, supra, at p 398; see, also, Roths-child v Title Guar. Trust Co., 204 N.Y. 458, 464, supra; Restatement, Contracts 2d, § 90, Comment a), and the long-established principle that "where one of two innocent persons must suffer by the acts of a third, he who has enabled such third person to occasion the loss, must sustain it" (National Safe Deposit Co. v Hibbs, 229 U.S. 391, 394, quoted with approval in Bunge Corp. v Manufacturers Hanover Trust Co., 31 N.Y.2d 223, 228). Estoppel does not render the mortgage valid but prevents "one who has represented it to be valid from asserting that it is void, to the injury of those who have acted in reliance upon the representation" (Claflin v Boorum, 122 N.Y. 385, 389; Valentine v Lunt, supra). The policy of the usury statute is not, however, ignored, for the innocent assignee is permitted to recover only the amount advanced with interest, rather than to enforce the mortgage for its face amount (Miller v Zeimer, supra, at p 446; Payne v Burnham, supra, at p 74; Bennis v Thomas, 14 A.D.2d 895; Klein v Meisels, 254 App. Div. 603; see Osborne, Mortgages, § 111, p 273; Ann., 165 ALR 626, 717).

The conduct or certificate must, however, have influenced the assignee to accept the mortgage to his injury (Payne v Burnham, supra, at p 73). That means not just reliance upon the existence of the certificate, but on the facts expressed by or implicit in it (Wilcox v Howell, supra, at p 403; see Claflin v Boorum, supra; Weyh v Boylan, supra; Hyde Park Terrace Co. v Jackson Bros. Realty Co., 161 App. Div. 699; Ann., 110 ALR 451, 462). An assignee who takes with knowledge can no more enforce the mortgage, whether as to principal or interest, than could the usurer. Knowledge by the assignee of the usurious nature of the transaction will, therefore, defeat an estoppel claim (Riggs v Purssell, supra; Gleason v O'Neill, 234 App. Div. 264; Merwin v Romanelli, 141 App. Div. 711).

The rules thus developed concern, it is true, so-called civil usury, as the Appellate Division noted, but were developed in relation to a statute (3 Revised Statutes [5th ed], part 2, ch 4, tit 3, § 5, now part of General Obligations Law, § 5-511, subd 1), which provided that a transaction in which interest in excess of the prescribed rate was taken "shall be void." Moreover, they became the established rules not without some hesitation and the realization that they trenched upon the policy of the usury law (Miller v Zeimer, supra, at p 445; Payne v Burnham, supra, at p 72; Ferguson v Hamilton, supra, at p 439).

Ascertainment of the legislative intent behind enactment of section 190.40 of the Penal Law and subdivision 3 of section 5-521 of the General Obligations Law upon the policy behind which the Appellate Division relied, requires consideration of the decisional law background above set forth, of which it may be presumed the Legislature was aware and, to the extent it left it unchanged, that it accepted (Transit Comm. v Long Is. R.R. Co., 253 N.Y. 345, 354-355; Orinoco Realty Co. v Bandler, 233 N.Y. 24, 30; People v Colozzo, 54 Misc.2d 687, affd on opn below 32 A.D.2d 927). Also to be considered are the facts that for 115 years, from the passage of chapter 172 of the Laws of 1850 until 1965, corporations were prohibited from interposing "the defense of usury in any action" (see Rosa v Butterfield, 33 N.Y. 665) and that until 1965 there existed, for practical purposes, no criminal sanction whatsoever for usury, whatever the effective rate of interest charged (Seventh Ann Rep of Temporary Commission of Investigation, Legis Doc, 1965, No. 100, p 72; Hechtman, Practice Commentaries, McKinney's Cons Laws of NY, Book 39, Penal Law, § 190.40; Note, 66 Col L Rev 167, 170). The April, 1965 Report of the New York State Commission on Investigation entitled An Investigation of the Loan-Shark Racket (particularly pp 22, 29, 82-84) brought to the attention of the Governor and the public the need for change in both, as well as for change in the immunity statute, and for provisions making criminal the possession of loan-shark records and increasing the grade of assault with respect to the "roughing up tactics" used by usurious lenders to enforce payment (id., at p 84). That report was studied by the Attorney-General, the Superintendent of Banks and the Governor's counsel, who, working with the State Commission of Investigation (see the Governor's Message of Approval, N Y Legis Ann, 1965, pp 509-510), prepared an administration memorandum (NY Legis Ann, 1965, pp 46-50) which was sent to the Legislature with the bill which ultimately became chapter 328 of the Laws of 1965. With respect to the provision which became subdivision 3 of section 5-521 of the General Obligations Law, that memorandum stated: "The bill would also provide that corporations may interpose the defense of usury in actions to collect principal or interest on loans given at interest greater than twenty-five percent per annum. This measure is vital in curbing the loan-shark racket as a complement to the basic proposal creating the crime of criminal usury. As noted above, loan-sharks with full knowledge of the present law, make it a policy to loan to corporations. The investigation also disclosed that individual borrowers were required to incorporate before being granted a usurious loan. This is a purely artificial device used by the loan-shark to evade the law — an evasion which this proposal would prevent. Furthermore, it would be most inappropriate to permit a usurer to recover on a loan for which he could be prosecuted." (Italics supplied.)

Noteworthy is the fact that though the Legislature authorized the pleading of criminal usury as a defense by a corporation (General Obligations Law, § 5-521, subd 3), it made no change in the provisions of section 5-511 declaring "void," as to individuals and other entities as well as corporations, any instrument reserving interest in excess of the legal rate although it must be deemed to have been aware of prior decisional law holding such an instrument enforceable, as above set forth, when an estoppel certificate has been given. It could, of course, in light of that case law, have abolished estoppel in pais as related to an estoppel certificate given to a criminal usurer by a mortgagor, or limited the effect of such a certificate as it had done in the second unnumbered paragraph of subdivision 2 of section 5-521 of the General Obligations Law. It made no mention of estoppel certificates and limited its statement of the civil purpose of the amendments made to proscription of recovery by "a usurer * * * on a loan for which he could be prosecuted." Its failure to close off the estoppel certificate avenue as a means for a usurer to realize on his illegal loan may have been an oversight, though in view of the case law history above detailed that hardly seems likely. Equally probable is it that the Legislature, recognizing the "two innocent persons" rule, was unwilling to penalize by the loss of both principal and interest an assignee who in good faith reliance on the mortgagor's assurance of the absence of any defense had purchased the obligation, because the Legislature believed limitation of the assignee's recovery to what he paid plus legal interest to be a sufficient deterrent to make purchasers of mortgages wary of professional usurers and a sufficient protection to the mortgagor who by certifying the absence of a defense has made transfer of the mortgage by the usurer possible.

So to suggest is not, as the concurrence and the Appellate Division indicate, abhorrent to public policy in any way. To the contrary, it is abhorrent to the policy of the law in the name of public interest to make an innocent assignee pay for the crime of the usurer in order to protect the borrower who, by his conduct or estoppel certificate, has misled the assignee. It is, moreover, wholly unnecessary to do so. People v Young ( 207 N.Y. 522) makes clear that the victim of criminal usury cannot by accepting restitution affect in any way the People's power to prosecute and that rule applies as well to estoppel by conduct or by certificate. The criminal usurer continues, therefore, to be subject to prosecution for a class E felony, the maximum prison term for which is four years. He remains subject also to civil liability for his criminal act; to the assignee who has been defrauded through the usurer's obtention of a false estoppel certificate for the difference between the face amount of the bond transferred and what he has been able to collect on it from the debtor; to the debtor from whom the usurer could have collected neither principal nor interest for the principal and interest which the debtor has been required to pay to the innocent assignee, the debtor not being in pari delicto with the usurer. Neither public welfare nor the public policy declared by chapter 328 of the Laws of 1965 is denigrated one whit by the limited recovery permitted to an innocent assignee; to the contrary, the public interests are vindicated fully, both civilly and criminally. Indeed, to relegate the assignee to an action against the usurer, as the concurrence suggests, is to denigrate the two innocent persons policy by turning that long-respected rule completely on its head.

Nor by so holding do we infer from legislative silence alone the adoption of decisional law (cf. Boys Market v Clerks Union, 398 U.S. 235, 241), for there is here clear and vigorous legislative action addressing the criminal usury problem in all aspects but this one. It is, rather, a recognition of the principle that "the intention to change a long-established rule or principle is not to be imputed to the legislature in the absence of a clear manifestation" (Matter of Delmar Box Co. [Aetna Ins. Co.], 309 N.Y. 60, 66; accord Shapira v United Med. Serv., 15 N.Y.2d 200, 218; see McKinney's Cons Laws of NY, Book 1, Statutes, § 153), especially when the change affects title to property or rules of liability (Seligman v Friedlander, 199 N.Y. 373, 376). Public policy determined by the Legislature is not to be extended by a court by reason of its notion of what the public policy ought to be (Waddey v Waddey, 290 N.Y. 251, 256; see Straus Co. v Canadian Pacific Ry. Co., 254 N.Y. 407, 413-414). Moreover, though estoppel in pais is a doctrine of judicial rather than legislative origin and thus subject to change by us, we do not believe that we would be justified in making a change predicated upon the criminal usury provisions of chapter 328 of the Laws of 1965, when the Legislature itself did not see fit to do so and the result would be unfair to an assignee who has acted in good faith reliance on an estoppel certificate (cf. Codling v Paglia, 32 N.Y.2d 330, 344-345). The Legislature may, of course, still change the decisional rule should it deem that desirable or wise.

Accordingly, we reject the Appellate Division's basic premise and hold that, until the Legislature otherwise provides, a valid estoppel certificate executed by a mortgagor and relied upon in good faith by the assignee of the mortgage will preclude the assertion of usury, whether civil or criminal, as a complete defense.

III

We are thus brought to consideration of the issue of duress which the Appellate Division found it unnecessary to decide. What we consider, of course, is duress as it affects execution of the estoppel certificate, and the first thing to be noted is that duress in obtaining the certificate is irrelevant unless the mortgage itself is found to be usurious and, therefore, void and unenforceable but for the estoppel. This means that the provisions of the mortgage permitting the mortgagee to accelerate principal and interest for failure to give an estoppel certificate, though sanctioned by subdivisions 2 and 7 of section 254 of the Real Property Law, will not obviate the claim that the certificate was obtained by duress.

In Wilcox v Howell ( 44 N.Y. 398, 402, supra) we held that estoppel does not operate to preclude an obligor from asserting that the instrument claimed to estop him was obtained by fraud (accord Laurel Realty Co. v Galasso, 6 A.D.2d 889; see Weyh v Boylan, supra, at p 401), and the applicability of that rule to duress has been recognized in Oleet v Pennsylvania Exch. Bank ( 285 App. Div. 411; see, also, Uniform Commercial Code, § 3-305, subd [2], par [b]). Those holdings having been part of the decisional law complex in light of which chapter 328 of the Laws of 1965 was enacted, and the strong-arm tactics of loan-shark enforcers having played such a prominent part in the Report of the State Investigation Commission, the conclusion must be that the Legislature intended no change of prior law in this respect.

Duress in obtaining the estoppel certificate will, therefore, invalidate it. We are not unaware of the effect of that holding upon the marketability of mortgage assignments, but conclude that estoppel being essentially a doctrine arising from inequitable action or conduct, the rule should not, absent legislative change, be applied when the mortgagor's action or conduct has been coerced (cf. Mandelino v Fribourg, 23 N.Y.2d 145, 148). Whether an estoppel certificate has been obtained by duress will generally be a question of fact, turning not just upon whether there was a threat to foreclose, but upon whether the trier of fact concludes from the circumstances surrounding the bargaining between the parties to the giving of the certificate or to the conduct relied upon and relative to the bargaining positions of both that the mortgagor acted under the influence of fear and would not have done so otherwise (see Restatement, Contracts 2d, §§ 174-175; 13 Williston, Contracts [3d ed], § 1604; 2 N.Y. PJI 900-901).

IV

The Appellate Division, applying the formula set forth in Band Realty Co. v North Brewster ( 37 N.Y.2d 460), concluded that the true interest rate was 27.7% per annum and, therefore, clearly in excess of the maximum prescribed by section 190.40 of the Penal Law. However, in concluding as a matter of law that the mortgage was criminally usurious, it overlooked the facts, outlined above, testified to by Ira Schwartz, that raised a triable issue of fact concerning whether the $2,100 was in fact a legitimate commission. True, the finder's fee is a device often resorted to by unscrupulous lenders (1965 Report of State Investigation Commission, Investigation of Loan-Shark Racket, pp 73-75). But a commission payable to Schwartz as agent for Foursome (with whom he testified he had an agreement) would not necessarily make the transaction usurious (Salvin v Myles Realty Co., 227 N.Y. 51; Guardian Mut. Life Ins. Co. of N.Y. v Kashaw, 66 N.Y. 544; cf. General Obligations Law, § 5-531; see Ann., 52 ALR2d 703; 32 N.Y. Jur, Interest Usury, §§ 67-69). Usury must be proved by clear evidence as to all its elements and will not be presumed (Giventer v Arnow, 37 N.Y.2d 305; Brown v Robinson, 224 N.Y. 301; Grannis v Stevens, 216 N.Y. 583). Whether the commission was a cover for usury was, therefore, a question of fact (London Realty Co. v Riordan, 207 N.Y. 264, 266) which the Appellate Division could neither assume nor decide. An additional reason why summary judgment should not have been granted to defendant is that, defendant's motion to amend its answer to assert criminal usury having been denied by Special Term, plaintiffs had neither reason nor opportunity to submit proof on the question whether the $2,100 paid to Ira Schwartz was a true commission. Fortuitously defendant's papers on the motion to amend supplied the omission by annexing Schwartz' deposition, but had that not been so it would, nevertheless, have been improper to grant summary judgment to defendant under CPLR 3212 (subd [b]) in view of the state of the pleadings as the matter reached the Appellate Division. The papers before that court were also sufficient to require plaintiffs to come forward with more than the bare statement that an estoppel certificate had been given, to show that they acted in reliance upon the facts it stated and without knowledge of the commission deduction which defendants allege made the transaction usurious, and to respond to defendants' claim of duress.

For the foregoing reasons, the order of the Appellate Division should be modified and affirmed, with costs, as above indicated.