Is it illegal to record a conversation with someone without their permission for court use?

Its not illegal to record someone, however, what you have recorded could possibly not be allowed to be used in court.   The Court is going to want to know how the recording was made, who had control of the recording, etc. The court will want to be sure that there isn't a possibility you could have tampered with the recording some how.  You will also need to have a way to identify who is speaking in the recording.  So it could be difficult to be given permission from the court to use the recording.