Illinois has a chance to fix its state finances, thanks to federal relief. But unless pension growth is brought under control, both retirees and taxpayers will be at risk as debt continues to consume state services.

The years 2010 through 2019 will go down in Illinois history as a decade of public policy failure and economic decline. High fixed costs for pensions and government worker health care have prevented the state from balancing its budget in any year since 2001. Since the Great Recession in 2008, the state’s fiscal imbalance has...