Why would leading apparel brands and retailers—like Zara, Tommy Hilfiger, and American Eagle—walk away from a life-saving inspection program that is the only effective worker safety initiative in their global supply chains?

The Rana Plaza apparel factory collapse killed more workers than any other manufacturing disaster in human history. The 1,134 known deaths in that building on April 24, 2013, a culmination of more than a decade of mass fatality incidents in Bangladesh’s sprawling garment industry—all in factories producing for leading global brands.

The most important thing to understand about this worker rights catastrophe is that most of buildings in which workers died en masse were covered by apparel brands’ own factory inspection programs. These “corporate social responsibility” programs, the brands claimed, were put in place to protect worker rights and worker safety. The abject failure of these purely voluntary schemes was readily quantifiable, from the 29 deaths in December of 2010 at That’s It Sportswear, a Gap, PVH, and Target supplier, to the 113 known people who died making garments for Walmart, Disney, KiK, and other brands at Tazreen Fashions in November of 2012 (among more than a dozen other tragic examples). Indeed, thousands of factory inspections under the brands’ programs of voluntary self-regulation never succeeded in identifying, much less addressing, the hazards that were killing workers, even though these hazards—inadequate fire exits, shoddy wiring, weak structural columns—were obvious to any competent safety engineer.

Today, the Bangladesh garment industry is vastly safer than in 2013, for one reason: the public pressure arising from the worldwide revulsion over the Rana Plaza collapse enabled unions and labor rights organizations to convince more than 200 apparel brands and retailers to sign the first binding and enforceable safety agreement in the contemporary history of the garment industry. The Accord on Fire and Building Safety in Bangladesh swiftly identified more than 100,000 deadly safety hazards across the 1,600-plus factories covered by the program and set about overseeing the renovations necessary to make these factories safe. Much of that work is done, though crucial pieces remain.

The Accord worked, where a hundred voluntary programs that preceded it did not, because the brands’ commitments are legally binding; because truly independent inspectors, not brand flacks, run the program; and because the Accord has the power to force brands to pay for safety renovations and to pull business from factories that refuse to carry them out.

Unfortunately, the very elements that make the Accord effective at saving lives—enforceability, independent oversight, constraints on brands’ choice of suppliers—do not sit well with the people who run those corporations. The Accord represents genuine regulation of brands’ labor practices, the kind of regulation they sought to escape when they shifted production from their home countries to Asia and Latin America decades ago. The brands would like that regulation to end.

The Accord is set to expire on May 31. Unions and labor rights advocates have proposed a binding successor agreement that will continue the Accord model in Bangladesh—where it has averted hundreds, probably thousands, of worker deaths and where many factories still need renovations—and expand the model to other countries where garment workers’ lives are routinely put at risk, including Pakistan, India, and Cambodia.

Brands and retailers want none of this: they refuse to sign a binding agreement; they want to turn over safety inspections of their factories in Bangladesh to a voluntary body; and they will not support any international programs unless the independent inspectors are brought under the control of the brands. The Accord interrupted the apparel industry’s otherwise relentless global drive for ever-cheaper labor and production costs. The brands crave an end to the interruption. The math is simple: if the brands get their way, more workers will die.