JP here is short for Justice of the Peace. In Britain this is a person who sits in a local court and hears smaller cases — small crimes, some family matters, whether someone should stay in jail before a bigger trial. Many are not career judges, and many are not paid. They can still send some people to prison, but they do not run the huge trials you see in films. In some other places, especially parts of the United States, a JP may also marry people or sign papers. Taiwan does not have this job. If you hold onto “a local judge for smaller things,” you will not go far wrong for the British meaning. Though actually, the title sounds grand — justice, peace — and students sometimes imagine a top judge. It is a local, everyday kind of court power.