In other words, a party who claims that the other party is silenced from raising a certain claim because of the existence of silence due to silence, has the burden of proving the existence of three elements: the existence of a representation, which is implied by the silence of the party claimed to be silenced; the reliance of the other party on this representation, which has changed its situation for the worse; and the existence of circumstances for which the creator of the presentation was tacitly obligated to disclose the information, the failure to provide which created the reliance of the other party ( Shlomovitz, paragraph 32 of the judge's judgment D. Barak-Erez; Civil Appeal 8453/09 Keren v. Israel Discount Bank Ltd., paragraph 28 of the judge's judgment A. Fogelman [Nevo] (2.1.2012); Friedman & Cohen Contracts A, at p. 92).
- In her opinion, my colleague points out, the judge G. Kanfi-Steinitz, on two main difficulties in the aforesaid argument of the appellant: The first, his concern is that the claim of estoppel is used, for the most part, only as a defense claim, i.e., as a "shield" claim and not as a "sword" claim. The second, concerned with the difficulty of recognizing the existence of a duty of disclosure that the respondent would have had to disclose to the appellant his aforesaid state of mind regarding the infringement proceeding and his intentions as to his future consent to use the fertilized eggs. This is done both in principle and on the concrete level, taking into account the circumstances of the case at hand.
- As to the first difficulty that my colleague Justice points out G. Kanfi-Steinitz - Indeed, in the case law of this Court it was noted that, fundamentally, the doctrine of estoppel by virtue of representation, that estoppel by reason of silence is only a specific manifestation of it, serves as a "shield" argument and not as a "sword" argument (Matter Ron, paragraph 20 of the judge's judgment A. Procaccia). This assertion was based on the roots of the doctrine in English law, from which our legal system drew the aforementioned doctrine, and which saw it as a doctrine rooted in procedural law, in such a way that its use may prevent a discussion of a particular claim, but not give rise to an independent cause of action (see: Gabriela Shalev and Effi Zemach Contract Law 95-96 (4th ed. 2019) (hereinafter: Peaceful and Plant); Friedman & Cohen Contracts A, at p. 626).
However, in the academic writing, it was noted that: "The distinction between estoppel as a cause of defense and estoppel as a cause of action raises difficulties" (Name, at p. 628). Thus, it was noted that determining the boundary line between cases in which the claim of estoppel serves as a ground on which the plaintiff's claim is based, and cases in which it serves as a procedural claim intended to block a defense claim by the defendant, is a difficult task to perform (Name). In this context, it is not superfluous to note that case law has held that raising a defense claim by the plaintiff does not, in and of itself, cut its classification as a "sword" claim (see, for example: Civil Appeal Authority 187/05 Naseer v. Municipality of Upper Nazareth, IsrSC 66(1) 215, 257 (2010); Appeal Petition/Administrative Claim 8832/12 Haifa Municipality v. Yitzhak Salomon in Appeal Taxes [Nevo] (15.4.2015); Civil Appeal 5831/24 Dor v. Migdal HaZohar Building Ltd., paragraphs 9-11 [Nevo] (11.2.2025)).