A district court judge has ruled that the tax system Texas uses to finance public schools is unconstitutional.

Judge John Dietz ruled in favor of more than 600 school districts responsible for educating three-quarters of the state's 5 million-plus public school students.

After a trial that took more than three months, Dietz determined the Legislature has not adequately funded schools as required under the Texas Constitution. In 2011, the Legislature cut $5.4 billion in funding by rewriting the formula used to distribute state money.

Dietz ruled from the bench and is expected to provide a detailed opinion later. The attorney general's office is expected to appeal the case to the Texas Supreme Court.