Human trafficking and slavery, particularly of children, has been an intractable global problem that defies an easy government solution, especially at the state and local levels. But California has just adopted a new law that could begin to make a difference, by taking aim at the economic beneficiaries of slavery — namely, manufacturers and retailers whose international supply chains perpetuate the abuse of workers in their foreign factories and facilities...The new California Transparency in Supply Chains Act, effective as of Jan. 1, applies to any company with $100 million in worldwide sales and some connection to California — which could be a statewide chain of stores or a single processing and distribution plant.The law commands businesses to make full disclosure about their supply chains and whether they regularly check them for possible slavery or trafficking conditions — and if so, what they do about it. The disclosure requirement is significant. Companies must disclose whether they conduct audits that might protect workers — including children — from slavery, and whether they require suppliers to abide by standards of morality and decency...The answers to these questions must be publicly — and prominently — displayed on a company's Web site, or in writing upon request. Companies must carefully determine how and what information to put on their Web sites.