When citizens are called to serve on a legal panel in court, that's called jury duty. When you're on jury duty, you have a responsibility to contribute to a verdict in a legal case.
Have you ever wondered how people end up on a jury? The answer is simply that it's their turn for jury duty. When a citizen gets a notice that they've been called for jury duty, they are legally obligated to serve, unless they have a very good excuse. Being called for jury duty doesn't always mean you'll be on a jury, thought, since potential jurors are questioned by the attorneys first and may be dismissed for a variety of reasons.