HARRISBURG, Pa. - It's a Pennsylvania court case now seven years delayed.

The argument is over fair funding for public schools and the disparities among them, particularly low-wealth school districts, where students of color are primarily concentrated.

The lawsuit was brought in 2014 on behalf of six low-income school districts as well as several parents and civil rights groups.

"They're attempting to minimize the efforts that we're putting forward relevant to this issue," said state NAACP President Kenneth Huston.

A Commonwealth Court judge heard two pre-trial motions Wednesday.

One seeks to prevent petitioners from offering any evidence or argument at trial that discusses racial disparities in public education. The other intends to block the inclusion of most evidence that relates to the past seven years.

"We want the judge to deny that request and to allow us to put in evidence of how students of color are faring in the system and demonstrate how underfunding is causing the impacts that we're seeing," said Claudia DePalma, an attorney for the Public Interest Law Center.

Governor Tom Wolf proposed a $1.5-billion increase in state education funding, and advocates say the state should use its budget surplus to invest in underfunded schools.

But some say legislative leaders are ignoring these pleas. We reached out to some of those leaders, who said they can't yet comment, as the matter is in ongoing litigation.

The Commonwealth Foundation, a free-market think tank, says state spending per student is far above the national average, and that taxpayers already pay enough.

"At the end of the day, I think the outcome that I'd like to see is legislative changes that allow money to follow the child and go with the child to whatever school they choose and whatever is best for their needs," said Nathan Benefield, vice president and COO of the Commonwealth Foundation.

The trial is scheduled to begin on September 9.