摘要
本文以買賣契約之危險移轉為研究主題，以聯合國國際商品買賣公約（CISG）為研究對象，探究危險移轉之法理本質。雙務性是雙務契約基本法理之一，有給付才有對待給付，危險移轉前發生引致危險之事由，則衍生出賣人是否繼續原給付義務或生次給付義務問題，買受人是否須為對待給付依雙務性法理即可推知，學理上一般將之稱為危險負擔。危險移轉前，各種法律效果皆契合雙務性法理。而危險移轉後發生引致危險之事由，買受人無從請求出賣人履行原給付義務或次給付義務，其對待給付義務卻並不因未獲得符合債之本旨之標的物而得以免除，此結果似乎與雙務性法理不符。 目前中文文獻大多誤以為危險移轉是與危險負擔有關之議題，實際上，二者並不相關，後者本質是「契約拘束力」問題，前者本質是「契約不利益之分配」問題，並不關涉契約「契約拘束力」與雙務性法理。危險移轉後，由於契約拘束力維持而非消滅，買受人基於契約拘束力，須繼續履行己方原定義務。 CISG關於危險移轉立法方式極為新穎，危險移轉時間點用語棄用大多內國法所用之「交付」（deliver）這一極具契約義務意味之術語，此即隱含了危險移轉作為契約不利益分配之本質及分配所依據之法理——契約風險範圍。並割裂契約履行問題與危險移轉問題，不產生混淆危險負擔和危險移轉之可能。 長久以來，學界對契約不利益分配之正當性基礎有過諸多嘗試，本文認為應從契約風險範圍著手探討，縱使在德國已有「契約風險範圍」類似理論出現，但並未成功建構，本文認為失敗原因是法釋義學之侷限，因而轉向經濟分析研究方法。由於外部性存在，公共部門介入市場可改善其運作結果，本文暫且聚焦於出賣人（廠商）生產成本層面，通過分析其邊際成本，指出界定契約風險範圍之可能方向。
並列摘要
The thesis mainly focuses on the passing of risk in sales contract in the United Nations Convention on Contracts for the International Sale of Goods (CISG). Synallagma is one of the basis principles in contract law which means only when the party performs his duty soundly can he gain the performance of the counter-party. Once the misfortune happens before the risk passes, it comes to the question that whether the seller has to redeliver or not, besides, whether he is liable to the damages. It can be deduced that the buyer’s obligation according to synallagma. Normally, it is described as assumption of risk in theory. Things become weird after the risk passes, however. The buyer can no longer claim for performance or damages once the risk passes to him, what’s worse, he has to continue his original duty according the contract. It seems to go against to synallagma. There are plenty of articles which take the position that the passing of risk has something to do with the assumption of risk. This paper has opposite view on the issue. The later refers to the truth that the parties are bound to the contract but the former means an distribution of loss caused by catastrophe which has nothing to do with synallagma. Once the risk passes, the buyer has to perform his duty due to the valid contract. The approach employed by the CISG is advanced especially in the passing of risk in that it waives the term deliver which has a sense of performance of contract. It implies the nature and the principle of passing of risk: the extent of contract risk. What’s more, it splits up the issue of performance of contract and the passing of risk which helps to clarify the issue of assumption of risk and the passing of risk. There has been a lot of efforts to justify the issue of distribution of the loss in contract for a long time. This paper insists that we should start with the theory of the extent of contract risk which has been failed to be defined in Germany with another similar appellation. One probable cause of such failure might be the shortness of Rechtsdogmatik and consequently, this paper turns to economic analysis of law to look for a new way to make it reasonable. The public sector can optimize the operation of the market due to the externality. This paper pays close attention to the cost of production of the seller and analyze its marginal cost to point out the possible way to build the theory of the extent of contract risk.