Jury duty is one of the responsibilities of citizens of the United States. Since everyone has a right to be tried by a jury of his peers, so too those peers have the responsibility of being on a jury. However, sometimes things happen and you need to reschedule your jury duty. Family emergencies, medical requirements or other difficulties that would otherwise make it impossible for you to attend to your jury duties need to be reported as soon as possible so that you can get your dates altered.
Examine your letter for jury duty requirements. There will be a list of contact information for the issuing court, including phone number and address. Some courts have an online contact as well, but not all do.
Contact the court and inform them you need to reschedule your jury duty. Whether it's because you will be out of the country, you have a family emergency or you have a health procedure scheduled for that day, your reason has to meet with the approval of the court.
Get a copy of the agreement to have your jury duty rescheduled. It's important that you check back with the court five business days or so after the change was reported to be sure that it's listed in the system. This way you can be sure that you won't be penalized for the necessary rescheduling.