AUSTIN -- Months of testimony in the sweeping school finance trial concluded Wednesday, with an advocate for charter schools arguing that courts should compel the Texas Legislature to increase the number of charter schools allowed to operate statewide and to increase the funding such schools receive.David Dunn, executive director of the Texas Charter Schools Association, was the trial's last witness.Closing arguments are scheduled for Monday, and state District Judge John Dietz has promised to issue a ruling immediately after that.Testimony began Oct. 22 with a three-week holiday recess in December.More than 600 school districts responsible for educating three-quarters of the state's 5 million-plus public school students sued the state, saying financial support provided by the state Legislature in 2011 was inadequate and unfairly distributed. The lawmakers slashed public education funding and educational grant programs by $5.4 billion.Joining those lawsuits are charter school operators, who say their campuses should receive additional state support to cover facilities costs, something they are not entitled to currently. They also want the Legislature to eliminate a cap on the number of licenses issued for charters statewide -- now set at 215 -- or at least to increase the number.Dunn said that, to his knowledge, if Dietz finds that Texas is obligated to provide facilities funding, it will be the first such decision of its kind in the country.This case is the sixth of its kind since 1984, but the first time charter schools have sued.Whatever Dietz decides will likely be appealed to the Texas Supreme Court. But if the courts eventually side with school districts, it will be up to the Legislature to overhaul its funding mechanisms.About 200 charter operators run more than 500 campuses statewide. They are privately operated but are considered public schools and educate about 3 percent of Texas students. It is legal to open more than one campus under a single charter school license.Dunn acknowledged that it will be up to the Legislature to relax the cap and allow money for charter school facilities. He argued, however, that charter schools' past lobbying efforts on both fronts have been unsuccessful, but the courts could order lawmakers to act.Dunn said the number of students on waiting lists for charter schools has jumped from about 56,000 in 2010 to about 101,000."We're not asking for a perfect system," he said. "We're asking for a fair system."During cross-examination, Dunn was asked if he could name operators who want to open charter schools but have been unable to do so because of the cap. He said that he couldn't, but would be able to soon because about 100 operators are seeking the six remaining available charter school licenses.