"We are reviewing the decision to determine what impact [it] has on our union," said Hetty Rosenstein, New Jersey director of the Communications Workers of America, which represents similar workers.
How Harris came to be affiliated with a union in the first place was at the crux of the case. It relates to the complicated employment structure of people like Harris, who besides being a mother also receives Medicaid money, paid by the State of Illinois, on an hourly basis to care for her son.
For that reason, the Supreme Court described Harris as a "partial-public employee." In Illinois and other states around the country, some partial-public employees are represented by unions.
"This is a major defeat for government-employee unions, but a big win for families in Illinois and across the country," said Paul Kersey, director of labor policy for the Illinois Policy Institute, which worked with the National Right to Work Foundation to shepherd Harris' case to the Supreme Court.
"It's a terrible decision," Rosenstein said, "and is a continuation of fewer and fewer Americans being eligible or able to unionize."
When Service Employees International Union Healthcare Illinois and Indiana won the right to represent home-care employees a decade ago, Harris did not join the union. She didn't have to pay union dues, but Illinois law still required her to pay a "fair-agency" fee to the SEIU.
Such fees represent what it costs a union to provide workers services, such as contract negotiation and handling of grievances. Rosenstein said about 85 percent of union dues covered such services; the rest covers political and organizing activities.
Though the Harris case involved home-care workers, in New Jersey and Pennsylvania, some "partial-public employees" run home day-care centers. They are paid with state-funded child-care vouchers given to parents who hold low-wage jobs and receive public assistance.
Pennsylvania's "partial-public" home-care workers are not represented by a union, said SEIU Pennsylvania Healthcare director Neal Bisno. About 5,000 home-care workers are unionized, but they are employed in the private sector, he said.
The court's decision comes as public-sector union representation is declining. In 2013, 7.9 million people were represented by public-sector unions, with 7.2 million of them members, down from 2012.
Employment lawyer Joel Barras, a partner at Reed Smith's Philadelphia office, who represents management, said that for unions, "it's going to be a significant hit financially." They will still have to provide union services to the workers, but won't be compensated for them.
Justice Samuel A. Alito Jr. wrote the majority opinion, joined by Antonin Scalia, Anthony M. Kennedy, Clarence Thomas, and Chief Justice John G. Roberts. Justices Ruth Bader Ginsburg, Stephen G. Breyer, and Sonia Sotomayor joined Justice Elena Kagan, who wrote the minority opinion.