On March 23, 2015, a lawsuit was filed accusing cash-strapped Chicago of denying due process to thousands of motorists issued red-light and speed camera tickets over a 13-year period.

Six weeks later, Mayor Rahm Emanuel quietly moved to change the rules in the middle of the game.

Without fanfare, Emanuel asked the City Council to amend Chicago’s municipal code to drop the step that attorney Jacie Zolna’s lawsuit had accused City Hall of skipping.

No longer would the city be required to send a second notice of violation prior to issuing a determination of liability against motorists slapped with speed camera and red-light camera tickets.

READ MORE: Judge says red-light, speed-cam tickets ‘void’; city violated due process

In addition to abolishing the second notice requirement that Zolna had accused the city of ignoring, City Hall made an administrative change to correct another due process violation cited in the lawsuit filed on behalf of three ticketed motorists.

Instead of assessing late penalties whenever motorists don’t pay up within 21 days of a liability determination, the city started abiding by the 25-day grace period required by law.

On Thursday, Zolna branded the after-the-fact changes an “admission of guilt” by the city, which strengthens his claim to refunds for motorists ticketed since 2003.

“It shows that they know what they were doing was unlawful. But instead of doing what they’re supposed to do, they just changed the law. That’s a little scary to me. It’s almost like an abuse of power,” Zolna said.

“It’s like playing a board game with a 6-year-old. Here’s the rules of the game and, when they’re caught cheating, they just change the rules. I guess they have that power because they’re the city. But, that’s not the way our country should be run.”

Law Department spokesman Bill McCaffrey acknowledged that both changes were made just weeks after the lawsuit was filed.

But he had no immediate comment on Zolna’s claim that the after-the-fact changes amount to an “admission of guilt” that strengthens the attorney’s claim.

The case appears to be plenty strong already.

Last week, a Cook County Court judge accused Chicago of violating the “fundamental principles of justice, equity and good conscience” by issuing thousands of red-light and speed camera tickets in a manner that denied motorists due process.

Technically, Judge Kathleen Kennedy simply rejected the city’s motion to dismiss the case, keeping Zolna’s lawsuit alive.

But the wording of her ruling was so strong, there is little doubt thousands of red-light and speed camera tickets issued since 2003 will ultimately be nullified, potentially forcing the city to refund hundreds of millions of dollars in fines and penalties already paid.

“The second notice provision is designed to protect a non-responding violator’s right to contest a violation before determination of liability issues,” the ruling stated.

“Therefore, the term `shall’ means mandatory in the second notice provisions . . . Because the second notice requirement at issue is mandatory under the [municipal code of Chicago], the determinations of liability are void and subject to collateral attack.”

Kennedy ruled that the three named plaintiffs in the case — Delyn McKenzie-Lopez, Themasha Simpson and Erica Lieschke — had “sufficiently alleged facts showing that the city’s retention of payments from determinations made without a second notice violates the fundamental principles of justice, equity and good conscience.”

“The alleged practice of accelerating late fees without statutory compliance is sufficient to show a violation of the fundamental  rinciples of justice, equity and good conscience,” the judge wrote.

Armed with Friday’s ruling, Zolna plans to forge ahead with his request for class-action status.

Zolna is also seeking an injunction that would prevent the city from collecting on or otherwise enforcing outstanding speed and red-light camera violations issued under the flawed procedure that denied motorists their due process.

“These debts should be wiped off the books. Debt collectors [hired by the city] should be on notice that they’re collecting invalid debt and could face $10,000 penalties,” the attorney said.

Although months of discovery lie ahead to determine precisely how many motorists are eligible for refunds, Zolna said he’s confident that the cash-strapped city will ultimately be forced to cough up as much as $200 million in fines and late fees, potentially with interest.

The city’s decision to thumb its nose at its own due process laws, then change the rules in the middle of the game, follows a federal corruption trial that proved the nation’s largest red-light camera program was built on a $2 million bribery scandal.

Last month, the former CDOT managing deputy who oversaw the red-light camera program was convicted of taking up to $2 million in bribes from Arizona-based Redflex Traffic Systems.

During the trial that lifted the veil on a red-light camera program built on bribes — not public safety — federal prosecutors proved that John Bills was getting a kickback of up to $2,000 for every new camera added to a network that became the largest in the nation.

Even after a 20 percent reduction, much of it ordered by Emanuel during last year’s heated mayoral campaign, Chicago has 306 red-light cameras at 151 intersections.