The witching hour is fast approaching for thousands of Chicago’s oldest retired city employees, barring an 11-hour legal rescue.

On Dec. 31, Mayor Rahm Emanuel will complete a 3-year phaseout of the city’s retiree health care program, including a 55 percent subsidy.

The controversial move is aimed at saving Chicago taxpayers $107 million in annual costs that would have ballooned to $307 million by 2018 and $541 million by 2023 if left unchecked, a mayoral commission had warned.

But it means that roughly 10,000 city employees who started working for the city before April 1, 1986, and do not qualify for Medicare will be on their own to search for coverage that will be difficult or too expensive to find.

They will be forced to choose between exorbitant premiums that, in some cases, are double their retirement checks or go without health insurance coverage at a time when they need it the most because of their age and declining health.

“We have people who are 75 years old who worked for the city for 30 years and more and none of them qualified for Medicare coverage. They’re being dumped into an abyss,” said Clint Krislov, lawyer for the retirees.

Krislov noted that the city is referring non-Medicare-eligible retirees to a Blue Cross-Blue Shield program at a monthly cost of either $1,295 or $1,466 for single coverage; $2,305 or $2,610 for a couple; and $3,138 or $3,622 for family coverage.

“The city has managed to drag this out and run out the clock. We have petitions, briefs and motions at all three levels of Illinois courts asking them to block the city and pension funds from turning off this coverage at the end of the year,” Krislov.

The mayor’s office had no immediate comment.

Mike Underwood, a retired Chicago Police officer with Parkinson’s disease, is the lead plaintiff in the lawsuit. He was shot, stabbed and suffered numerous broken bones while serving as a police officer in the Austin neighborhood.

Underwood said he turned 65 last year. His wife turned 65 last month. Both are covered by Medicare.

But he feels “horrible” for the 10,000 retirees who are not Medicare-eligible.

“Two thousand-six hundred dollars for a couple is more than some people take home in their entire payment,” Underwood said. “Without Medicare, I don’t know how people can afford it. I guess they go to County [Stroger] Hospital.”

Last summer, Circuit Judge Neil Cohen issued a mixed-bag ruling that threatened to prevent Emanuel from completing the 3-year phaseout.

Cohen ruled that the lifetime health care coverage of 22,000 people who started working for the city before Aug. 23, 1989, is protected by the Illinois Constitution’s pension protection clause. It states that those benefits “shall not be diminished or impaired.”

Cohen subsequently ruled that the pension funds have primary responsibility to provide a health care plan for their participants. The city was merely on the hook to subsidize at some level.

The judge dismissed the lifetime benefits claim made by retirees who started working for the city after Aug. 23, 1989. He argued that they began working under a statute that provided benefits only for limited periods of time and that those periods have expired.

But Cohen subsequently refused to enjoin the city from ending the coverage on Dec. 31.

That leaves the ultimate decision in the hands of an Illinois Supreme Court that decided a similar case in favor of state retirees, citing that same protection clause in the state Constitution.

In May 2013, Emanuel announced plans to extend the retiree health care subsidy until Jan. 1, 2014, then phase it out by 2017 to relieve Chicago taxpayers of a $108.7 million a year burden they could no longer afford.

At the same time, the mayor announced that 4,638 of the oldest and most vulnerable retirees would be guaranteed health care coverage with a 55 percent subsidy for as long as they live.

Union leaders and retirees blasted the mayor for forcing retirees to fend for themselves under the Affordable Care Act at the same time he was using $125 million in public money to build a new basketball arena near McCormick Place.

Retirees then flexed their legal muscle by filing a class-action lawsuit that has played out in the courts ever since.

During his Oct. 11 budget address to the City Council, Emanuel lumped the phaseout of the retiree health care subsidy into the pot of “tough decisions” he has made to cut the city’s structural deficit by 80 percent.

“How did we get this done? We took on entrenched interests in some cases and inertia in the system in others that were preventing us from making some tough decisions and common sense choices,” the mayor said on that day. “We saved $100 million in health care costs, and our employee health care budget is level with 2011.”