由於各國法制差異，為解決涉外法律關係中所應適用何國法律問題，各國國際私法於焉產生。而當事人意思自主原則(the Principle of Party Autonomy)業成為各國國際私法所普遍採用之選法原則於國際商務契約與海商契約案件中扮演極為重要之角色。蓋契約之債為涉外債權關係之主要發生原因，因各國關於契約之債實體法規定並非出於同一立法者，並於其法域各具其效力，致使同一涉外契約法律關係適用當因法域不同而有不同之結論，殊有礙於當事人預先準確遇見法律行為效果之可能性，職是之故，雙方當事人事先協議確定涉外契約關係之準據法，於訂立契約時即能清楚瞭解其權利義務我適用何國法律實至關重要，我國涉外民事法律適用法第六修即明訂：「I法律行為發生債之關係者，其成立要件及效力，依當事人意思定其應適用之法律。II當事人意思不明時，同國籍者依其本國法，國籍不同者依行為地法，行為地不同者以發要約通知地為行為地，如相對人於承諾時不知其發要約通知地者，以要約人之住所地視為行為地。III前項行為地，如兼跨兩國以上或不屬於任何國家時，依覆行地法。」本條之正確適用實攸關我國國際貿易及海商案件之處理，然就本條之運用則我國實務見解迴異學說及國外見解，殊值研究。

　　　　　Private international law is designed to deal with the question of when and why the courts of one jurisdiction take into consideration the elements of foreign law because of the discrepancy in different legal systems. Furthermore, the importance of party autonomy is multiplied because of different laws. In choice-of-law decisions, there is but one basic policy, namely, protection of the expectations of the parties. Such predictability is served, and party expectations are protected, by giving effect to the parties' own choice of the applicable law. Party autonomy means that the parties are free to decide the law governing their contract, subject to certain limitations. This principle is articulated in paragraph 1, article 6 of ROC's Law governing the application of laws to civil matters involving foreign elements which provides: "The applicable law of contractual obligations shall be decided by the principle of party autonomy." Since this article is numerously invoked in court decisions on international trade and maritime issues, a study to correctly apply this article is worthwhile in view of the fact the supreme court of ROC interprets this article in a sharp contrast to those of both civil law and common law countries and scholars. Since private international law derives the concept of the party autonomy from western jurisprudence, most ROC's scholar in this regard illustrates this concept by invoking relevant international well-known cases instead of the supreme court decisions of ROC. Therefore, there is virtually no study on the review of the application of the concept of the principle of party autonomy in the supreme court decisions of ROC. Accordingly, with a view to upgrading decisions quality by combining scholarly theories with judicial practices, this study will center on reviewing the supreme court decisions.