Preparing for trial can be difficult for witnesses. The nature of the legal system is such that trials will usually take place years after the events in question occurred, and witnesses’ memories are not frozen in time. Witnesses may meet with counsel to prepare, but testimony is not a prepared speech.

Judges are experts on the law, not only as a matter of practice, but as a matter of principle. They know the law because they deal with it on a daily basis; they are also deemed to know the law because the law itself says so.