More than 80 percent of the members of a Michigan union representing home health care workers opted to quit the organization in 2013, federal filings show. The workers took advantage of the state's newly enacted right-to-work law, which allowed individuals to opt out for the first time ever.

SEIU Healthcare Michigan, a branch of the powerful Service Employees International Union, saw its membership drop from more than 55,000 in 2012, to just under 11,000 in 2013, according to Labor Department data. The decline happened the same year Republican Gov. Rick Snyder signed the right to work law.

The sheer size of the shift suggests that a majority of SEIU Healthcare Michigan's members never wanted to be in the union in the first place. The federal data indicates that those opting out are primarily people who participate in the state's Home Help Services program. The program subsidizes people who provide health care for others, usually family members, in their own home.

In 2005, then-Gov. Jennifer Granholm, a Democrat, created the Michigan Quality Community Care Council -- commonly referred to as "MQC3" -- ostensibly for the purpose of keeping tracking track of program's 45,000 participants. However the entity also made it legally possible for the state to claim the participants were actually employees and therefore eligible for collective bargaining.

The following year, Granholm signed a collective bargaining contract with SEIU Healthcare Michigan, after a mail-in ballot in which only 20 percent of the program participants voted. It is not clear how many in the program even knew an election was going on or what the ballot represented.

"This evidence shows the truth about the Granholm-inspired unionization of those in the home help program," said Patrick Wright, director of the free market Mackinac Center Legal Foundation, which first reported the union's federal filing. "When given the choice, those in the program didn't want to give the union a dime."

A representative of the union could not be reached for comment.

As their caregivers' representative, the union received about $6 million annually in membership dues. The money was collected for it by the state, taken directly out of payments to the caregivers.

Federal data shows that a majority of those funds in 2012 went to spending on union political activities and lobbying, not collective bargaining. The union was fined more than $200,000 in March by the state for violating campaign finance laws 2012, the second-largest in state history. The spending was primarily to back a state ballot initiative which would have codified the union's arrangement with MQ3 in the state constitution. The union used a front group called Home Care First to conceal its spending.