(CBS) — The Illinois Supreme Court has heard arguments in the Emanuel administration’s attempt to save its pension deal with some city employee unions, reports WBBM Political Editor Craig Dellimore.

The state Supreme Court has already ruled that Illinois law can’t reduce existing pension benefits for state employees but in Springfield, Chicago Corporation Counsel Steve Patton argued that the city pension agreements are different because the unions agreed that the city will pay more and more into the fund guaranteed in exchange for pension adjustments.

“Here, the benefits of membership in these funds is not diminished or impaired, they are preserved and protected,” Patton said.

But attorney John Shapiro representing the plaintiff says that this argument misses the point.
“Setting aside money to pay what is already a constitutional guarantee is not a benefit new or net,” he said.

But Patton says the pension system will collapse without this law.

The state’s highest court will rule on this case at a later date.