在通謀虛偽意思表示及因被詐欺而撤銷其意思表示之情形，雖然表意人與相對人間所為之物權移轉，因意思表示無效或被撤銷之結果，不生物權移轉之效力，但不知情之第三人卻仍自未取得該權利之相對人受讓該權利者，善意不知情之第三人，就其因交易而受讓之權利，原本即可在法律保護交易安全之前提下，主張依善意受讓之規定，而受保護。然我民法卻在此善意受讓制度之外，就通謀虛偽意思表示及因被詐欺而撤銷其意思表示之法律效果，另設有不得對抗善意第三人之規定，以為對交易安全的保護。此一對交易安全保護之重複規定，依現今通說，亦存在於單獨虛偽意思表示之情形，亦即單獨虛偽意思表示為相對人所明知而為無效時(§86但) ，應類推適用通謀虛偽意思表示之規定，而不得以其無效對抗善意第三人。此外更由於民法第九十二條第二項在文義上僅係就「被詐欺而為之意思表示，其撤銷不得以之對抗善意第三人」而為規定，就該條文之反面解釋，卻可獲得因被脅迫而撤銷其意思表示者得對抗善意第三人之結論，對於善意第三人財產之取得，影響不可謂不深。凡此關於「不得對抗善意第三人」之規定，均形成典善意受讓制度之保護目的相互重疊，甚而有所衝突之情形，究竟「不得對抗善意第三人」之規定在我國現行民法體系上具有何特殊意義？其規定與善意受讓間之關係如何？對於交易安全之保護是否有此重複規定之必要？實有就法律釋義(Rechtsdogmatik )及比較法( Rechtsvergleichung )之觀點，在我國現行法之體系範圍內，針對立法者所為之規定可能產生的疑點，加以檢討之必要。

Where a manifestation of will has been rescinded on the ground that it was made either by sham transaction or by fraudulent misrepresentation, the bona fide third person could still acquire such a title from the other party (the recipient) who has no right over thing, despite the transfer of the right over thing between the manifestant and the recipient could not go into effect resu1ting from void ab initio or rescission declarating by the manifestant. The third person in bona fide could be otherwise entitled to enjoy its right acquired from transaction, under the rule of bona fide acquisition of ownership, which is designated to ascertain transaction security. Nevertheless, other than the institute of bona fide acquisition of ownership, Taiwan's Civil Code provides that the effect of nullification or rescission, to the manifestation of will made either by sham transaction or by fraudulent misrepresentation, shall not prejudice the interest of the third person in good faith, so that it could facilitat e the security of transaction. As stated in the most jurists' opinions, such repetitious stipulations to assure transaction security could be found in the provisions regulated the manifestation of will made under mental reservation. On the other hand, courts shall apply the provision of sham transaction analogically to the manifestation made to a person who is aware of the reservation (under Taiwan Civil Code §86 proviso), without prejudice the third person in good faith. Furthermore, because the literal words of Civil Code §92 II merely provides that “[t]he effect of rescission to a manifestation of will induced by fraudulent misrepresentation shall not prejudice the third person in good faith," it could be interpreted as “[t]he effect of rescission to a manifestation of will induced by duress shall otherwise prejudice the third person in good faith," by argument of contradict. As a result, the effect brought by this proviso to the acquisition of ownership is significant. All of the provisions conc erning “not to prejudice the third person in good faith" come into overlapping with the legislative purpose underlying the institute of bona fide acquisition of ownership: in addition, they are contradictory to each other. What is the exact meaning of “not to prejudice the third person in good faith" in the Civil Code? What is the relation between this stipulation and bona fide acquisition of ownership? Is it necessary to stipulate this proviso repetitiously so that transaction security could be assured? Indeed, it is necessary to review the potential issues, derived from statutes enacted by the legislature, in light of the context of statutory language and comparative law, to the extent that the construction of our current law would be.