Mandatory Jury Duty is unconstitutional. It violates the 13th amendment which says:
Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.
Involuntary servitude is being coerced into working against one's will in the service of another. The coercion can take the form of threats of physical violence, imprisonment, or fines. Failure to report to jury duty is punishable by fines and/or imprisonment and is therefore involuntary servitude.