By Gene Johnson / Associated Press

SEATTLE — The Washington Supreme Court has narrowly upheld an $18 million fine levied against an association of large food brands that funneled dark money into a state political campaign.

The 5-4 decision Thursday found that the penalty against the Grocery Manufacturers Association — now known as the Consumer Brands Association — did not violate the U.S. Constitution’s ban on excessive fines. The association said it would petition the U.S. Supreme Court to review the case.

The group, which included companies like Coca-Cola and Nestle, in 2013 collected $14 million from its members. It then contributed $11 million of that to help defeat a Washington ballot initiative that would have required labeling of genetically engineered ingredients on food packaging.

The association failed to register as a political committee in the state, did not disclose which companies contributed the campaign money and filed no campaign-finance reports until after Attorney General Bob Ferguson sued.

As part of the lawsuit, the state uncovered evidence that one association executive noted during a meeting that having a pooled campaign account would “shield individual companies from public disclosure and possible criticism.”

“The GMA’s offense struck at the core of open elections,” Chief Justice Steven González wrote for the state Supreme Court’s majority. “The grave nature and broad extent of GMA’s offense suggests the penalty is not grossly disproportional.”

The dissenting justices, led by Justice Sheryl Gordon McCloud, said that the association’s failure to file campaign disclosure reports was serious for a reporting violation but that it was only a reporting violation. She called the $18 million penalty “grossly disproportionate” to that offense.

The justices previously found that the Grocery Manufacturers Association’s violations were intentional, but sent the case back to a lower court to determine whether the fine was excessive. The Eighth Amendment to the U.S. Constitution prohibits excessive fines.

“This is a victory for fair and transparent elections in Washington, and a defeat of special interest dark money,” Ferguson said in a statement.

Consumer Brands general counsel Stacy Papadopoulos said in an email that the association was disappointed in the ruling.

“The state’s legal process has been tainted by partisan politics, and the ruling in this case will chill core political speech by legitimate organizations based on their viewpoints,” the statement read. “The only winner in this decision is politics — not the law, the facts or the American public.”

The GMO-labeling measure, known as Initiative 522, failed by a vote of 51% to 49%.