House Republicans, with tacit support from the Trump administration, have unveiled their latest effort to stick it to working people. They’ve introduced a bill that would eliminate a crucial legal protection for the growing number of Americans who work in the “contracted out” economy.

The Republicans have set their sights on gutting “joint employer” responsibility. Their bill would allow companies to dodge responsibility for their workers simply by hiring them through a labor subcontractor. If workers are stiffed of wages owed or want to form a union, the company can conveniently point the finger at someone else and say, “Not my problem.”

Employer evasion is a problem in growing sectors of our economy that are seeing increased labor outsourcing. Millions of workers today are no longer sure who their boss is. They include janitors, home care workers, construction drywallers, warehouse lumpers, and agricultural and garment workers, some of whom are placed by temp or staffing firms, while others are at the bottom of a long chain of subcontracting.

If workers don’t know who their employer is, work conditions are more likely to deteriorate: pay declines, wage theft increases and workplace injuries rise. Outsourced jobs pay less – sometimes as much as 30 percent less than in-house jobs. In today’s economy, we should be looking for ways to increase workers’ pay and economic security, not laying the groundwork for more sweatshops.

Real-life examples of this “who’s the boss” accountability problem abound: A temporary worker on his first day on the job at a Bacardi bottling plant in Florida died when he was crushed in a machine; Bacardi said it was the temp agency’s sole responsibility. Corn detasselers in Indiana sought unpaid wages from the farm labor contractor, who disappeared; the court said they could recover their pay from the grower, who, despite exercising control over the whole operation, argued it wasn’t responsible.

Joint employment only comes into play in these cases when the temp agency or the labor contractor can’t pay or disappears. And not all contracting relationships give rise to joint employment. There has to be some power to control the job from “the mother ship” (as one former Labor Department wage-and-hour chief puts it).

Our nation’s labor and employment laws have long had the notion of joint employment – that more than one entity can be responsible for fair pay and safe workplaces if the other is not stepping up. These rules don’t bar companies from outsourcing; they simply mean that the companies cannot outsource responsibility for their workers.

Given how deeply ingrained joint employment is in our nation’s labor and employment laws, why do House Republicans feel a need to address the issue now?

The National Labor Relations Board’s Browning-Ferris decision from 2015 gives us one clue. In that case, the employer, Browning-Ferris Industries, called in a staffing company to bring in 240 workers to a recycling plant. When the workers wanted to unionize for better pay and working conditions, Browning-Ferris Industries refused to bargain and said it was the staffing agency’s responsibility. But the staffing agency wasn’t calling all of the shots and could not deliver. The NLRB found that Browning-Ferris Industries was a necessary party at the bargaining table as a joint employer. So some of today’s joint employer frenzy comes from anti-union forces.

The use of contractors and subcontractors has a long history in the agriculture, construction, and garment industries. But the practice is spreading into other areas, and nowadays, often the only way to get a job in manufacturing, warehouses and tech is through a staffing or temp agency. Companies like Amazon, Nissan and Google, just to name a few, use temp agencies to source some of their workers.

Corporations that engage low-road contractors and then look the other way gain an unfair advantage over companies that play by the rules, resulting in a race to the bottom that rewards cheaters. It’s one reason why the job quality of what were formerly middle-class jobs in America is suffering today.

Responsible contracting companies operating under these rules for decades know what to do: Ensure that violations do not occur in their business by contracting with reputable contractors, and by monitoring compliance and taking corrective action if needed.

This op-ed was originally published in U.S. News and World Report.