1. The problem asks which constitutional amendment guarantees the right that citizens uphold by reporting for jury duty. 2. Jury duty is related to the right to a fair trial, which is part of the criminal justice process. 3. The Sixth Amendment guarantees the right to a speedy and public trial by an impartial jury. 4. Therefore, the constitutional right upheld by jury duty is guaranteed by the Sixth Amendment. **Final answer:** Sixth Amendment