A group of Illinois retailers is making a last-ditch effort to halt the rollout of Cook County’s sweetened beverage tax, calling it confusing and “unconstitutionally vague” in a lawsuit filed Tuesday.

The group, headed up by the Illinois Retail Merchants Association, plans to ask a judge Wednesday to declare the tax invalid and issue a temporary injunction to stop the July 1 rollout.

“It doesn’t give guidance of how people in practice are supposed to enforce this tax ordinance,” said Jordan M. Goodman, a lawyer representing the group. “There’s a lot of confusion. And we’re seeing that by the county reacting in the last month, making significant — if not 180-degree changes — to how realtors are supposed to enforce the tax.”

The suit argues, among other things, that there would be a double standard when it comes to imposing taxes on soda and some other sweetened beverages. At a coffee shop, for example, the tax would apply to a bottled sweetened beverage but not to one prepared by a barista behind the counter.

“They are not treating like things alike, and that is a major concern for us — and we frankly think it’s illegal,” said Tanya Triche Dawood, vice president and general counsel for the Illinois Retail Merchants Association.

Said Frank Shuftan, a spokesman for Cook County Board President Toni Preckwinkle: “We intend to aggressively defend our position and the ordinance in court.”

That tax covers carbonated soft drinks, whether sweetened with sugar or a substitute such as aspartame. It also covers sports drinks and energy drinks. Fruit drinks will be taxed, too — but 100 percent fruit juice drinks are exempt.

Because some sweetened drinks are taxable and others aren’t, imposition of the tax fails to live up to the stated goal, according to the suit, which is to “promote public health and reduce obesity rates.”

Collecting these “unconstitutional” taxes could also open retailers up to lawsuits, Goodman said.

“We’re putting our retailers in a horrible situation where it’s a no-win situation,” he said. “What we really want to do is take a step back, try to analyze this tax, come up with solutions — and a July 1 date just isn’t going to work for us.”

TAX PASSED: Cook County OKs penny-an-ounce tax on sweetened beverages

Earlier Tuesday, a protest against the tax was held outside the Thompson Center.

About 200 protesters showed up. Some own mom-and-pop hotdog stands. Others run sprawling grocery stores. Still others work on bottling machines.

Carol Bollacker owns two hot dog joints — one in Indiana and one in Cook County near the Illinois border in Lansing.

“The people who eat at my restaurant have choices,” she told the crowd. “I anticipate a decline in sales after July 1 because some of my customers will simply make the decision to drive a few miles into Indiana or Will County to pay less for their dinner there. The beverage tax is going to hurt thousands of Cook County restaurants.”

Faye Porter, 63, a retired state worker from the Bronzeville neighborhood. | Stefano Esposito/Sun-Times