(TNS) — The trial for a landmark case challenging how Pennsylvania pays for public education and highlighting deep disparities between wealthy and poor districts is underway, with the potential to affect every student, school, and taxpayer throughout the state.

The lawsuit — brought seven years ago by six school districts, including Delaware County’s William Penn; parents, including one from Philadelphia; and the Pennsylvania Association of Rural and Small Schools and the NAACP-Pennsylvania State Conference — alleges Pennsylvania’s school funding is both inadequate and inequitable, violating the state constitution.

At the heart of the case are wide gaps in resources between school districts — the product of a long-ingrained funding system that relies more heavily on local taxes than all but six other states and that plaintiffs say discriminates against children and burdens taxpayers in lower-wealth communities. Lower Merion, for instance, has more than $31,000 to spend per student because it can reap more in property taxes — even at lower rates — compared with poorer districts like William Penn, which has $18,000 per student.

Plaintiffs contend the funding system disproportionately harms children of color: Half of Pennsylvania’s Black children and 40% of Hispanic children live in the poorest 20% of districts.

“It’s a story where children who need the most often get the least,” said Mimi McKenzie, legal director of the Public Interest Law Center, which filed the lawsuit in 2014 along with the Education Law Center. Besides William Penn, the five other districts suing are the School District of Lancaster, the Greater Johnstown School District, the Wilkes-Barre Area School District, the Shenandoah Valley School District, and the Panther Valley School District north of Allentown.

The trial, which is being heard by a Commonwealth Court judge in Harrisburg, is being closely watched by schools statewide.

Over the next eight to 10 weeks, lawyers are expected to call dozens of witnesses, from local school administrators and state education officials to experts in funding, poverty and learning, testifying to mountains of reports and statistics on Pennsylvania’s public education system.

Nationally, court mandates have significantly shaped school funding. In 28 states where Supreme Courts’ decisions overhauled funding systems between 1971 and 2010, researchers found gaps between low- and high-income districts decreased, and linked spending increases to improved school quality and better student outcomes.

But any changes in Pennsylvania wouldn’t be immediate, given likely appeals. And if the court rules in favor of plaintiffs, it would likely fall to the legislature, which controls the state budget, to come up with a solution. That could result in an increase in or a reallocation of what the state spends on public schools, making property taxes a lesser piece of the funding pie — although it’s too early to know how that would pan out.

While plaintiffs say inadequate funding has led to poor academic results in lower-wealth districts, Republican legislative leaders who are defendants in the case argue more money wouldn’t necessarily lead to better outcomes.

They also point to Pennsylvania’s overall school-funding levels: The state ranks in the top 10 nationally in average spending per pupil, though it trails other Northeastern states including New York, Connecticut, New Jersey, and Massachusetts.

For a case all about money, the suing schools and the GOP opponents don’t seem to disagree all that much about funding figures.

Plaintiffs are citing a 110-page report by Matthew G. Kelly, an education professor at Pennsylvania State University, who found the state’s richest schools as a group spent nearly $5,000 more per year per student than the poorest. For his analysis, Kelly divided the state’s 500 public school districts into five groups with roughly the same number of students in each.

Kelly found that the wealthiest schools spent almost $22,000 per student annually vs. just under $17,000 for the least affluent. Lawyers for the GOP did not respond when asked whether they had a rival analysis to share.

Republicans indicate they will challenge that analysis as “deeply flawed” and unrealistic.

In court filings, Republican legislative leaders indicate plans to call expert witnesses who will say there is “no meaningful relationship” between what Pennsylvania districts currently spend and student test scores, and “no empirical consensus” that smaller class sizes boost student learning.