Two unions have filed a lawsuit in King County Superior Court attempting to stop implementation of Initiative 1183, which kicks the state out of the liquor business by June.

The unions represent nearly 1,000 workers expected to lose their jobs because of I-1183, which 59 percent of Washington voters approved in November.

The lawsuit says the measure violates a rule that requires an initiative to address just one issue. The legal tactic is common and sometimes successful.

Besides putting liquor in grocery stores, I-1183 also changes wine-distribution laws, changes the ability of the Liquor Control Board to regulate alcohol advertising and creates new franchise protections for liquor distributors, the lawsuit says.

"While it is not illegal for a private company to pay for an initiative and spend almost unlimited money to get it passed, it is illegal for them to abuse the system by loading the initiative with too many changes to the law. The reason for the single-rule clause in the constitution is to prohibit this very thing," the unions said in a release.

"Costco did it this way to hide the fact of these other provisions. And that is in essence the reason why the single-subject rule exists. To limit the deceitfulness, it requires the advocates for an initiative to be truthful about what is and is not in the initiative," said Tom Geiger, spokesman for United Food and Commercial Workers Local 21, which represents more than 700 liquor-store workers who would lose their jobs if the stores close.

Hundreds of Teamster workers also believe they would lose their jobs, because they distribute liquor and wine under the current system.

Geiger said his union is paying some of the legal costs to challenge I-1183. A spokesman for the Wine & Spirits Wholesalers of America, which contributed much of the $12 million spent to fight the voter measure, declined to comment on whether it will pay for any of the legal costs.

Costco spent a record $22 million to help pass the initiative through the Yes on 1183 campaign, which said the lawsuit is without merit. Costco's worldwide sales of wine, beer and spirits totaled $2.6 billion for the fiscal year that ended in August, and about a quarter of it — or roughly $650 million — was liquor.

"The cornerstone of the lawsuit, an allegation that the voters didn't understand the full implications of the initiative, is both insulting to Washington's citizens and ironic in light of the millions spent by the plaintiffs and their special interest allies on opposing privatization," the campaign said in a release.

Distributors oppose I-1183 because it tears down laws put in place after Prohibition that require retailers to use distributors when buying liquor and, to some extent, wine.

Daniel Okrent, who wrote the book "Last Call: The Rise and Fall of Prohibition," said distributors have long fought to keep their legally mandated place in the system.

"Now what you have is an incredibly powerful, well-financed lobby consisting of the distributors," Okrent said. "They have great influence in state legislatures and spend a lot of money to keep themselves in the system, and will come up with all kinds of reasons, some of which may make sense. But as with most things in our culture, profit is the primary motive."

The Liquor Control Board will continue implementing I-1183 unless a court orders it to stop, a spokesman said. It is on track to stop selling liquor by June 1, when grocery stores measuring at least 10,000 square feet will be eligible to sell it.

I-1183 officially becomes law Thursday.

It could be legally challenged after that, said Janelle Guthrie, a spokeswoman in the state Attorney General's office, which will defend the initiative as it does any measure passed by voters.

Legal challenges based on the single-subject rule are relatively common, said Mark A. Smith, a political-science professor at the University of Washington.

But he recalls only a couple of initiatives that were bounced on similar grounds in recent years. Both were Tim Eyman measures; in one case, the Legislature then enacted a law similar to the initiative.

Melissa Allison: 206-464-3312 or mallison@seattletimes.com. On Twitter @AllisonSeattle.