If you have received a summons for jury duty, it is important to know that your appearance is mandatory. The rules and potential penalties for missing jury duty vary by state and even cities where you live. Penalties can include both criminal and civil actions. If you decide to ignore the jury summons, you run the risk of fines or even jail time. The reality is that jail time would more then likely just add more burden to the judicial system and is a rare punishment, but with the right set of circumstances, it could happen. The more likely outcome is that you will be fined and served another summons for jury service.