The group said the recent decision by the U.S. National Labor Relations Board violates international labor and human rights laws.
"The NLRB ruling potentially deprives millions of workers of legal protection if they are fired for trying to organize unions or bargain collectively," HRW said.
"With this legal sleight of hand, the NLRB has created an ersatz category of employee -- people without the authority of real supervisors or management and without the rights of ordinary employees," said Jamie Fellner, director of the U.S. Program at Human Rights Watch. "Employers may be pleased, but with this ruling, the United States violates its labor and human rights obligations under international law."