我的理解seditious conspiracy 就是 conspiracy of sedition。虽然是望文生意，但看来挺合理的。

conspiracy表明只是起诉其“合谋”的一部分。不需要实际
实施了合谋的那个事情。合谋的是什么呢，这里合谋的是
sedition。sedition跟treason不一样，所以不该叫‘叛乱
的谋划。如果seditious conspiracy对应谋划叛乱那能不能
起诉谁conspiracy of treason呢？

我觉得treson conspiracy 应该是比setisious conspiracy
重的指控。

In the criminal law, a conspiracy is an agreement between two or more persons to break the law at some time in the future, and, in some cases, with at least one overt act in furtherance of that agreement. ...., in most countries, no requirement that any steps have been taken to put the plan into effect (compare attempts which require proximity to the full offence).

Though sedition may have the same ultimate effect as treason, it is generally limited to the offense of organizing or encouraging opposition to government in a manner (such as in speech or writing) that falls short of the more dangerous offenses constituting treason.