Editor’s Note: This article was reported by Daniel Wise, Jeff Storey, Noeleen G. Walder and Andrew Keshner, and was written by Mr. Storey.

The state court system is making elaborate preparations to cope with the unprecedented departure by Nov. 24 of hundreds of seasoned employees—an exodus that could bring months of turmoil but pay off in a long-term overhaul of operations, increased employee morale and a more diverse workforce.