“悬案”的词义为：长时间未能破获的案件，悬而未决的案件。

在搜寻了一番相关的英语法律术语后，我发现以下术语的定义与中文意义的“悬案”相符。

1.inactive case

“inactive case” 在英文法律中的 定义为：

"a pending case over which the court has no effective control, a case which is filed in court, but for some reason cannot be processed by the court."（已经起诉但法庭因为某种原因儿无法控制或进行审理的案件。）

2.pending case

如果最高法院完全承认有关司法豁免权，肯定可以解决所有悬案，包括针对巴西利亚办事处前主任和教科文组织的INSS 案。

Should the Supreme Court fully recognize the immunity of jurisdiction, this would definitively solve all pending cases, including the INSS case in which UBO former Director and UNESCO are cited.

3. outstanding case

例：

Where there has been no information from the Government or the sources, notwithstanding the annual reminder sent by the Working Group concerning outstanding cases, only the table is provided and a reference is made to the previous report dealing with those cases.

在政府或信息来源没有提供资料(尽管工作组每年都就一 些悬案发函提醒)的情况下，只提供列表，并指明处理这些案件的早期报告。 

4.unresolved case

例：

就此，根据黎巴嫩国对其公民的安全与保障以及其领土上居民的安全与保障所承担的固有责任，对于你为解决这一悬案所提供的任何帮助和援助将不胜感谢。 

In this regard, based on the inherent responsibility of the Lebanese State for the security and safety of its citizens, as well as that of residents on its territories, any help or assistance which you could provide to this unresolved case will be much appreciated.