system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why is jury duty mandatory in the US?
gpt
Because the US consitution (6th amendment) guarantees the right to a trial:

> by an impartial jury of the State and district wherein the crime shall have been committed

The only way of creating an impartial jury is by getting a random pick from the population, and not just people who want to serve on a jury .  If they only took volunteers, they wouldn't have enough people to guarantee a jury, and the ones they would get would either have plenty of free time, or like judging people.  Both qualities wouldn't meet the standard of an "impartial jury".