California found half a million returned jury duty solicitations (based on voting records.) The potential jurors said they weren’t American citizens, so they couldn't do jury duty...
There’s the ticket. Every registered voter should receive a jury summons during the two year period between elections. If they reply they can’t perform the duty because they are not a US citizen, they get purged from the voter rolls and flagged for deportation because they registered to vote. Then when the rest (legal citizens) call the number, the announcement says they are not needed.