Americans are fascinated with secret societies. From articles about the Illuminati to news reports on the Bilderberg Group, people love to speculate on furtive conspiracies.

Now imagine an organization so secretive, even its own members don't know they belong to it. It sounds absurd, but a half million Americans belong to this secret club. It's likely that every week you pass by or talk with a member of this covert group.

Does this organization make its members rich, famous or powerful? Nope. Belonging to this secret society actually makes you poorer.

The secret society is the Service Employees International Union, and its elusive members are home-care providers. The SEIU reports representing 600,000 dues-paying home-care providers, but government surveys show that only a sixth of them report having union representation. That makes a half million Americans paying dues to the SEIU who don't know it.

Every year the SEIU collects around $350 from each of these 500,000 individuals. That works out to almost $200 million a year going into the union's coffers.

Union officials have profited handsomely from this windfall. In 2011, Eliseo Medina, SEIU's international secretary-treasurer, took home $411,682 in total compensation, and Mary Kay Henry, SEIU's international president, took in $372,406 in total compensation. According to the SEIU's own tax records, both worked just 35 hours a week.

While these vast sums allow SEIU to pay its top officials top dollar, those unwittingly paying the dues make around $10 an hour caring for the nation's most vulnerable.

Home-care providers take care of individuals who cannot take care of themselves in their own homes. Medicaid funds pay them for this often-difficult work. In some cases these home-care providers work for a health care company, but usually a family member or friend provides the care.

The system is win-win. The taxpayers avoid paying for more expensive institutional care, while the program's recipients have greater freedom and independence in their homes.

State governments don't manage or hire or fire these providers - they are usually family members, not government employees. As such traditional labor unions simply don't fit into this picture. Would a mother to go on strike against her disabled son? Or children against their aged parents?

Nonetheless SEIU lobbied legislatures and governors redefine home-care providers as "public employees," usually for the sole purpose of extracting union dues from them. The SEIU succeeded in more than a dozen states.

This is why half a million union "members" simply have no idea they belong to a union. These states withhold union dues from their Medicaid reimbursement check. In most cases the union takes this money and does nothing else for them.

Robert Haynes, a frustrated home-care provider and parent of a special-needs child, complained about the SEIU: "We're not getting anything from them. We've tried to contact them, and they don't even bother to respond. I don't even know what they could do to help. Considering the dues money we're sending them, maybe they should come over and babysit our kids so we could have one night out."

Thankfully the Supreme Court has good news for members of this club. The court recently ruled in Harris v. Quinn that unions cannot force home-care providers to pay dues. Unfortunately the SEIU is unlikely to stop skimming money from their Medicaid checks unless home-care providers ask to exercise this right.

But how does someone leave an organization they don't even know they belong to?

That's where a nationwide effort called National Employee Freedom Week comes in. Running Aug. 10-16, this coalition of 68 groups, including The Heritage Foundation, in 40 states is informing workers nationwide about their right to leave their union through radio ads, billboards, online ads, flyers and social media. Or in the case of home-care providers, these organizations are informing individuals for the first time that they may be part of a union and how to leave.

Once this secret gets out, look for home-care providers to save hundreds of dollars a year by leaving the unions they never knew they belonged to in the first place.

Editor's Note: Victor Joecks co-authored this commentary.

 - James Sherk is a senior policy analyst in labor economics at The Heritage Foundation.

 - Victor Joecks is executive director of National Employee Freedom Week.