Governor Christie has not been charged in the case involving a traffic tie-up at the George Washington Bridge, but he will loom large in the story laid out by both sides in the courtroom.
Long championed as a lifeline for poor black children, the schools have recently been denounced by two civil rights organizations, which called for a moratorium on charters.
The New Jersey governor, who hoped to be Donald J. Trump’s running mate, saw his political fortunes crash after backing Mr. Trump in the presidential race.
Michigan leapt at the promise of charters 23 years ago, betting that more competition would improve public education. Instead, old problems grew worse.
Both testing companies have pushed into the market for federally required tests in public schools, offering them even to students who do not plan to go to college.