The Philadelphia Federation of Teachers and Philadelphia School District were sued in Common Pleas Court on Wednesday over a long-held practice that allows union employees to remain on the school system's payroll.

The conservative Fairness Center, representing Americans for Fair Treatment, holds that taking teachers and other school workers out of city classrooms to work for the PFT is illegal, despite the fact that the union pays the workers' salaries and benefits.

Technically, up to 63 PFT workers - including union president Jerry Jordan - are permitted to remain on the district's books, accruing seniority and pension time and receiving district health insurance. The union reimburses the district for the full cost of carrying the roughly 20 workers who are actually on the district's books, a spokesman said.

Jordan, in an interview, said that it was "unfortunate that this group chooses to malign people who happen to work for unions. To give the impression that we're doing something illegal is upsetting. They're just playing wrong."

Though the PFT reimburses the district its employees' salary, benefit and pension costs, the Fairness Center says the state has put about $1 million toward their benefits since 1999, it estimated.

The Fairness Center argues that the district and PFT have gone beyond the scope of their legal authority in striking this arrangement, and say it violates the state constitution because public money, in this case, is paying for private work.

The Fairness Center called Jordan and other workers "ghost teachers," and blasted the PFT for taking advantage of the district as it struggles with years of classroom cuts and significant deficits.

"Philadelphia students need all their teachers in the classroom - not ghost teachers getting paid to skip school and work for a union," Fairness Center general counsel David Osborne said in a statement.

Osborne also took issue the district for allowing the PFT workers to remain on its payroll. The school system agreed to grant certain PFT workers release time from district jobs in its most recent contract - which expired in 2013, though most of the terms of the pact are still being honored. The Fairness Center appears to object to the fact that the contract does not specifically require the union to reimburse the school system for the cost of carrying the workers, though it does so.

"In the cost-conscious world of Philadelphia education, it's stunning that the collective baraining agreement currently in place does not require the PFT to reimburse the district for any of these costs," Osborne said. "The district is effectively propping up the PFT machine and losing oversight over its own employees."

The practice of allowing union workers to remain on the public-sector payroll is common, but Fairness Center officials say they are suing to shine a light on the school system's "egregious" practice and have it declared illegal in Pennsylvania.

Americans for Fair Treatment is a new organization with headquarters in Harrisburg, focusing on citizens receiving "fair treatment from government unions." Its officials declined to say how many members belong to the group, which has also taken aim at the Pennsylvania State Education Association, a state teachers' union.

One Americans for Fair Treatment member, George Coates, said he objected strongly to the PFT practice.

"It does nothing to further the education of our children," said Coates, who works as a consultant in the wine and spirits industry and lives in Philadelphia.