A woman repackages plastic sprayers at a sheltered workshop for adults with disabilities. (Tammy Ljungblad/Kansas City Star/TNS)

Joe Biden, the presumptive Democratic candidate for the presidency, has promised to end the loophole in federal labor law that allows certain employers to pay employees with disabilities lower than minimum wage. An estimated 300,000 people with disabilities in the U.S. are paid subminimum wage. Six states have banned the practice already, but legislation to make the change apply nationwide has not received a vote in Congress.