unless and until在法律文件中一般以A unless and until B的形式出现，即A是否能够发生，取决于B。unless界定客观条件，until限定时间。看过不少中文翻译，一般都比较直，译为“除非或直至”“除非及直至”...，译者可能是考虑到严谨性，但译完总有种不是中文的感觉。如：

Where a person is convicted of an offence, any police officer may take or cause to be taken all or any of the identifying particulars of that person whether or not such particulars are already in the possession of the Commissioner, and the Commissioner may retain any identifying particulars so taken unless and until and conviction is set aside on appeal.

如有人因某项罪行而被定罪，任何警务人员均可取得或使人取得该人所有或任何的鉴证资料，不论该等资料是否已由警务处处长保存，而警务处处长可保留已取得的鉴证资料，除非或直至该人的控罪经上诉驳回为止。

在汉语表达中，“除非”一般和“否则”一起出现，如“除非明天晴天，否则我们不去动物园”，而“直至”一般与“为止”一起出现，如“直至天亮为止，他都没有看到极光”，所以，将unless and until译为“除非”或“直至”其中一个即可。我们可以在《元照英美法词典》中得到验证。

查阅《元照》可以发现，词典中给出的中文表达是“直到...为止”，并给出释义说unless和until两者并非同义词，在该词组中，until的含义包含了unless的含义，因此以until一词表述已足矣。

如：

Our records of such account and transaction and any use of the Internet/Phone Banking Services shall be conclusive unless and until the contrary is established.

除非能提供相反证明，否则均以本行对此等账户及交易以及任何使用网络/电话银行服务之纪录为准。

Unless otherwise agreed between you and us in writing, any change in, addition to or revocation of the Authorized Signatory and, the Specimen Signature(s) or the Signature Arrangement shall not take effect unless and until we shall have actually received such documents and/or authorizations in the form and substance satisfactory to us and reasonable opportunity to respond such change, addition or revocation.

除非本行与阁下另有书面协议，任何授权人员、签字式样或签署安排的任何更改、增加或撤销均不会生效直至本行已实际收到令本行满意的关于上述更改、增加或撤销事项的文件及／或书面授权及有足够的时间就上述各项作出更新。