Ab initio，常用于法律语境，表示“from the beginning自始；从一开始；starting from the beginning 从头开始的。如the ab initio design of a new car 新车从头开始的原始设计。The agreement was declared void ab initio. 此协议自一开始就被宣布无效。

Void ab initio，则为“自始无效”，自始无效是一项合同法律关系中广泛运用的制度，一旦某个合同或某项合同条款因违反法律或公共秩序而被宣告无效，那么宣告无效的效力将上溯到合同签订的那一刻起，即合同自始都是无效的。

相关法律法规：

《中华人民共和国民法总则》第一百五十五条规定：

无效的或者被撤销的民事法律行为自始没有法律约束力。

⑴自始无效。无效民事行为之无效，自行为开始起发生，该行为之意思，从开始起就不被法律所认可；

⑵当然无效。即无效民事行为，无需任何人主张，也不待法院或仲裁机构宣告，即无效。该行为无效不以主张、确认和宣告为要件；

⑶意思无效。无效民事行为之无效，是指当事人意思不发生效力，而不是说没有任何法律效力。

参考双语例句：

No person shall be eligible for election or to serve as a Director until there is registered in his name one or more shares in the Company provided that the election of a Director by the members in general meeting without share qualification shall be valid and shall take effect when he is registered as a member but if he is not so registered within two months of his election shall be deemed void ab initio and a casual vacancy shall be deemed to have arisen.

任何人士均须有一股或以上之本公司股份登记在名下，方符合资格获选或出任董事， 惟股东于股东大会上选举并无资格股份之人士为董事须于其已登记为股东之时为有效 及生效，惟倘其并无于获选后几个月内登记，有关选举得视 为 由最 初开 始 即 属 无 效 以及 视为因此而产生临时空缺。

Detection of health problems (with ab initio presentation at the different ages) which may benefit from early detection coordinated with specialist care by means of activities designed to ensure early detection of metabolopathies, hypoacusis, displasia of the hip joint, cryptorchidism, strabism, vision problems, puberal development problems, obesity, autism and attention deficiency and hyperactivity disorders, and also identification and monitoring of children with physical and psychological disabilities and chronic diseases

一些疾病在不同年龄事都可能表现出初期症状，应尽早检测出这些疾病并且给予专业治疗，从而使儿童获益，例如应尽早检测代谢疾病、听力损失、髋关节发育不良、隐睾症、斜视、视力问题、青春期发育问题、肥胖、自闭症、注意力缺陷及多动症，对于有生理残疾或心理 残疾的儿童进行检测及跟踪治疗，对于患有慢性疾病儿童进行跟踪治疗。

I hope the Government understands that if no authorization is issued and if confirmation cannot be obtained, it is then, from the very beginning ― ab initio, another unfamiliar term which may be Latin or Greek, for all these concepts are supported by long-time legal backing and thinking.

希望政府明白，如果没有获授权，无法确认，其实由开始 ─ 称为 ab initio，这又是我们不懂的文字，或许是拉丁文或希腊文，它们这些概念全部都有一个长久的法律依据及思考。