勞動契約不只是勞務給付與工資給付的對價關係，更是雇主與受僱人間人的結合。因此在勞動契約持續期間，雇主對受僱人除有工資給付義務外，還有照扶、尊重對待等義務；受僱人對於雇主則有忠實為勞務給付義務、遵守雇主指揮命令、保守秘密的義務。 勞動契約終止後，勞雇雙方的上開義務即終止。受僱人可能趁著離職的機會自行創設與雇主事業經營性質相同的公司或另行受僱於原雇主的競爭對手以獲取較佳的勞動條件；原雇主則可能視離職受僱人的此種行為構成不公平競爭而欲加以防止。雇主為預防受僱人離職後與其競爭，可以與受僱人簽訂限制競業協議，禁止受僱人於離職後於一定期間、地域內對雇主為商業競爭行為。 對於限制競業協議，不論是我國或是英國皆未有制定法予以規範。唯基於契約自由原則，既然受僱人自願接受限制，除非約定的內容有違法之情事，否則法律似無干涉的理由。然而，此種協議對受僱人謀生能力的影響甚鉅，故英國習慣法經過數百年來判決先例的累積而發展出「限制競業協議理論」，對於限制競業協議的內容加以干預、審查，以求保障受僱人的權益，並在嚴格的條件下兼顧雇主的合法財產上利益。本文的主旨即在探討習慣法上限制競業理論的發展及該理論在司法實務土的運用方法。 本論文共分六部分。第一部分在於將討論的主題由勞動契約引入限制競業協議及此種協議所產生的爭議；第二部分則在探討英國實務土常見的五種限制競業協議類型及個別類型的利弊及功能。第三部分則在討論司法介入限制競業協議的理論發展及干預的基礎，以支持後續章節的討論。第四部分則就英國法院對於限制競業協議的內容所採的解釋方法，及當認為協議內容超出合理限制必要時，如何利用切割的方式予以限制作探討。第五部分則討論合法之限制競業協議必須符合哪些要件，其中包括雇主應對受僱人之不競業承諾提供對債、雇主需具有合法財產上的利益，以及限制競業的期間、地域範園、顧客範固必須合理等。於第六部分，本文除重申法律干預限制競業協議以保護受僱人權益的必要外，並就我國法院對限制競業協議的態度及行政機關的相關函示予以簡短介紹，以突顯兩國法律在發展上的差異。

An employment contract is not only an exchange of labour and wages, but also an union between an employer and an employee. Thus, during the course of a contract of employment, apart from providing wages, an employer owns his employee a duty of care and a duty to treat him with respect. Meanwhile an employee has to serve his employer with loyalty, to obey the legitimate orders of his employer, and to exercise a duty of confidentiality. When an employment contract is terminated, both parties’ obligations towards each other end. A departing employee may take the opportunity to set up a rival firm or join a competitor to improve his terms and conditions of employment. His former employer may regard such a behaviour as unfair competition and may seek legal remedies against him. In order to prevent the former employee from engaging in unwelcoming competition, the employer might enter into a restraint of trade covenant with the employee, which sets out restrictions on time and/or space where the ex-employee cannot participate in any commercial activity similar to that of the employer’s. In both Taiwan and the United Kingdom, there is no statutory provision governing restraint of trade covenants. Base upon the principle of freedom of contract, once an employee voluntarily accepts restriction on his freedom to sell his labour, so long as there is no violation of law, there seems little the judiciary can do to intervene. However, a restraint of trade covenant seriously damages an employee’s opportunity to make a living. In the United Kingdom, after hundreds of years of the accumulation of precedents, the common law has developed the restraint of trade doctrine to tackle and scrutinize the contents of restraint of trade covenants. Its purpose is to safeguard the rights and interests of employees whilst, under strict conditions, to protect the employers’ legitimate proprietary interests. The main theme of this thesis is to explore the development of the restraint of trade doctrine and to discuss its application by the judiciary. This thesis consists of six sections. The first section starts with a brief discussion on the implied duties of employment contracts which is followed by explaining the necessity of restraint of trade covenants and their ensuing issues. Various types of restraint of trade covenants together with their advantages and disadvantages are examined in the second section. In the third section, the focus is on the development of the restraint of trade doctrine by the judiciary which explains the reasons behind judicial intervention and also provides a basis for further discussions. In the fourth section, this thesis tries to explain how the judiciary uses its power of construction and severance skill to trim excessive restrictions or even to render them void. In the fifth section, the conditions upon which a restraint of trade covenant can be justified are discussed in detail. It includes the requirement of consideration, the existence of legitimate proprietary interests as well as area of restriction, duration, and the scope of customers have to be reasonable. In the final section, this thesis emphasizes the necessity of legal intervention on the restraint of trade covenants and briefly describes the attitudes of the courts and the Council of Labour Affairs in Taiwan over restraint of trade covenants.