“有效”经常出现在合同的“可分割性条款”（severability clause）中，常见的表述有“若本协议的规定部分或全部变得无效或不可执行，这不得影响本协议其他规定的有效性。”“如果本协议的某条款或数条款，根据任何适用法律在任何方面是无效的、不合法的或不能执行的，则本协议的其他条款的效力、合法性和可执行性不受任何影响或损害，并仍然完全有效。”等。具体可参考如下双语例句：

Any provisions of the project agreement which are required by the context or are otherwise expressed to continue in force and effect notwithstanding the completion of the project or the suspension or termination of the project agreement.

即使项目已经完成或拨款协议已经终止，拨款协议的任何条文，不论是文意所示还是另有明示，均仍然继续有效和具作用。

If any one or more of the provisions contained in this Agreement shall be invalid illegal, or unenforceable in any respect under any applicable law, the validity , legality and enforceability of the remaining provisions contained herein shall no in any way be affected or impaired and shall remain in full force and effect.

如果本协议的某条款或数条款，根据任何适用法律在任何方面是无效的、不合法的或不能执行的，则本协议的其他条款的效力、合法性和可执行性不受任何影响或损害，并仍然完全有效。

Should provisions of this Agreement be or become invalid or unenforceable in part or in whole, this shall not affect the validity of the other provisions of this Agreement.

若本协议的规定部分或全部变得无效或不可执行，这不得影响本协议其他规定的有效性。

“无效”在合同中出现的场景比较多，常见的表达有两种：null and void和invalid and unenforceable，具体使用场景可参考如下实例：

If the conditions set out above are not fulfilled by a date falling ninety days after the date of the Agreement, being 11 February 2008, or such later date as the parties may agree, the Agreement will be null and void and of no further effect.

倘上述條件未能於協議日期後起計九十日之日（即二零零八年二月十一日），或訂約各方可能協定之較後日期達成，協議將告失效及無效，並終止效力。

The Court of Appeal confirmed this decision, but the Supreme Court, taking the opposite view, overturned it, stating that "a dismissal declared null and void, as in the case at hand, is supposed to have never existed and the employee is reinstated in his employment without further formalities".

上诉法院同意该决 定，但是最高法院做出了相反的裁决，推翻了下级法院的决定，宣判“像在上述案件中，当解雇无效时，就被认为是从未发生过，职员重新回到原来的工作岗位”。

Each of the provisions of these Terms is severable and distinct from the others and, if at any time one or more of such provisions is or becomes illegal, invalid or unenforceable in any respect under the laws of any jurisdiction, the legality, validity or enforceability of the remaining provisions shall not be affected in any way. 

本章則內之各項條文均可分割及獨立詮釋，即使任何條文因某法律管轄區之法律變成非法、無效或不能強制執行，其餘條文之合法性，有效性或應執行力均不受任何影響。

If at any time any provision of this Agreement is prohibited by law or judged by court to be illegal, void, invalid or unenforceable in any respect, that provision shall, to the extent required, be severed from this Agreement and rendered ineffective without modifying the remaining provisions of this Agreement and shall not in any way affect any other circumstances of or the validity or enforcement of this Agreement.

倘若協議的某些條文於任何時候被禁止或被法庭裁定不合法、無效或在法律上不能執行，此等條文將被視作從協議中分割出去及變得毫無效力，但不會因此而修改了協議的其他條文，而協議的其他情況、合法性及可執行性均不受影響。