rebut的释义为：to show or say that something is not true.

在英文法律协议中，常以被动形式出现，即 rebutted,，用来表示“（控诉、控告等）被反驳，（证据等）被推翻”之意。

例如：

Presumption can be rebutted, and if the defendant wants to rebut this presumption, he must produce evidences and take the defend liability.

推定具有可反驳性，被告要推翻控方的推定必须要提出证据证明，承担抗辩责任。

那么对于 “unless rebutted” 的理解和翻译，也要放在实例中比较好分析，此处摘取一股东协议中对股东名册的一些规定的英译中协议为例：

Under Cayman Companies Law, the register of members of our company is prima facie evidence of the matters set out in the register (that is, the register of members will raise a presumption of fact on the matters referred to above unless rebutted) and a member registered in the register of members is deemed as a matter of Cayman Companies Law to have legal title to the shares as set against its name in the register of members. Once our register of members has been updated, the shareholders recorded in the register of members will be deemed to have legal title to the shares set against their names.

 参考译文如下：

依照《开曼群岛公司法》，公司的成员名册构成其中记载事项的初步证据（即，除非提供反证，推定成员名册记载的上述事项是真实的），成员名册登记的成员视为依照《开曼群岛公司法》，对成员名册中登记在其名下的股份拥有法定所有权。公司成员名册更新后，视为成员名册登记的股东对成员名册中登记在其名下的股份拥有法定所有权。

在该实例中，并未将“unless rebutted” 译为“除非被反驳，” 而是更结合文意，灵活译为： “除非提供反证，”。