star witness 不能直译为“明星证人”，而应翻译为“重要证人”、“主要证人”或“关键证人”。

在法律程序中， a star witness is a witness who provides major and crucial information in a criminal case. In some instances, a case may have several star witnesses, and their testimony may cinch a conviction or acquittal, especially when handled by a skilled lawyer. The testimony of star witnesses is often a topic of interest for the general public as well, especially in high profile cases, and in open courtrooms, there may be a number of bystanders present to listen to the testimony of a star witness.

简言之，“Star Witness” 是一个用来描述在某个法律案件中具有关键重要性的证人的术语。这个证人通常因其对案件的直接知识、可信度或与案件相关的特殊见解而被视为极为重要。Star Witness 的证词通常对审判结果产生显著影响。

例如，在刑事案件中，Star Witness 可能是目击了犯罪行为的人，或者是对被告有不利证据的内部人士。在民事案件中，Star Witness 可能是能够提供关键事实或专业见解的专家。

具体的使用可参考如下双语例句：

The prosecutor presented the star witness, who testified to having seen the defendant at the scene of the crime.

检察官出示了关键证人，此人作证称在犯罪现场看到了被告。

The credibility of the star witness was challenged by the defense, as they pointed out inconsistencies in her testimony.

辩护方质疑了这位重要证人的可信度，因为他们指出了她证词中的不一致之处。