中文摘要：

尽管船舶优先权是物权,遵从法定原则,但是合同的约定依然有效。船东为了避免受此约束,往往在租约中加入一个禁止产生船舶优先权的条款。在全面分析美国法下这一条款有效和无效的典型判例的基础上,总结出判断其法律效力的基本原则。

英文摘要：

The contractual choice-of-law clause is valid in determining the existence of maritime lien,although the latter is a kind of real rights. The shipowner,however,may therefore insert a no-lien clause into the time charterparty in prohibiting the charterer＇s authority of lien binding the vessel under the time charterparty. This paper examines the validity of such a clause and its effects on maritime lien by analyzing the authorities under American case law,followed by a conclusion of the general principles in determining the same.