To be excused from jury duty, write a letter addressed to the clerk of the court requesting an excuse with an explanation of hardship. USCourts.gov offers a list of district court websites and a list of acceptable excuses.
The Jury Act allows courts to excuse a juror from service at the time that she is summoned on the grounds of "undue hardship or extreme inconvenience." A letter to the clerk of the court should outline the specific hardship that makes jury duty difficult for the individual to fulfill. While each court maintains its own procedures and policies, USCourts.gov explains that some groups do not have to serve when called. These groups include members of the armed forces on active duty, members of professional fire and police departments, and full-time public officers of federal, state or local governments. Some groups are more likely to be excused, such as people over the age of 70, people who have served on a federal jury in the last two years, people who volunteer as firefighters or members of a rescue or ambulance crew, full-time students who live far away and don't have transportation, and single parents. Excuses are granted at the discretion of the court and cannot be reviewed or appealed.