“This item may be the product of slave labor.”

Those jarring words could end up on candy bar wrappers, packages of frozen shrimp and even cans of cat food if some California lawyers get their way.

Forced labor permeates supply chains that stretch across the globe, from remote farms in Africa and the seas off Southeast Asia to supermarkets in America and Europe. Almost 21 million people are enslaved for profit worldwide, the UN says, providing $150 billion in illicit revenue every year.

Governments are pushing companies to better police suppliers, including proposed SEC reporting rules in the U.S. But that’s not enough for a group of U.S. law firms. They’ve sued name-brand companies doing business in California, like Hershey Co., Mars Inc., Nestle SA and Costco Wholesale Corp., hoping to use the state’s novel consumer protection laws to put the suffering of millions squarely in front of shoppers.

“These lawsuits are vehicles for forcing business ethics,” said Niall McCarthy, an attorney with one of the class action firms taking up the issue, Cotchett Pitre & McCarthy LLP. “You cannot ignore human suffering to make a buck.”

The companies say there’s no state law mandating warnings, and that they’re doing their best to avoid working with anyone using slave labor. This week, Nestle prevailed in Los Angeles, where a federal judge agreed there’s no requirement to warn consumers about seafood from Thailand. The lawyers behind that suit have vowed to appeal, while McCarthy’s firm will argue a similar case against Costco in San Francisco later this month.

A victory for consumer lawyers may force companies into a corner: Give shoppers a moral dilemma every time they go to the supermarket, or pay suppliers a lot more to eliminate any temptation to use slave labor.

Nestle Report

Forced labor in supply chains burst into public view after recent reports about the savage conditions some workers endure. Tales in the Guardian and Associated Press of indentured servitude on Thai fishing boats, where starvation, beatings and even murder can occur, triggered an outcry among human rights groups. The lawsuits soon followed.

Then, on Nov. 24, Nestle said forced labor taints Thailand’s seafood industry, part of the company’s supply chain for whole prawns. Consumer lawyers said it’s also a source of ingredients for Nestle’s cat food brand Fancy Feast. Nestle Executive Vice President Magdi Batato said at the time that the Swiss company is “committed to eliminating forced labor in our seafood supply.”