The motion was filed Tuesday in Lubbock, Texas. An in-chambers hearing was set for 8:30 a.m. Wednesday in the 99th District Court.
University officials suspended Leach on Monday while the school investigates a complaint from receiver Adam James and his family. James is the son of former NFL player Craig James, now a television sports analyst for ESPN.
A person close to James with direct knowledge of the situation contends the player was twice forced to stand in a small, dark place while the team practiced. The person spoke to The AP on the condition on anonymity because of the sensitive nature of the complaint.
And a person close to the inquiry said Leach was "begged to work something out to avoid a confrontation." The person spoke on condition of anonymity because the investigation is ongoing.
That person also said Leach late last week postponed a meeting related to the inquiry and refused to sign a letter saying "no one injured would be returned to work out without doctors' permission."
The school's attorney left a voice mail message with Leach's attorney late last week that the university needed a letter of apology by noon Monday, the person said.
It did not arrive.
"That's when they made the decision to suspend (Leach), thinking that would bring him to his senses," the person said.
In an affidavit included in the filing Leach said he "would never intentionally harm or endanger a player" and that he has been "forced into this situation without being afforded any process."
He wrote "absolutely" no evidence had been given to him that showed he had violated any university rules or standards.
"I have never and would never intentionally harm or endanger a player. I am committed to Texas Tech University and the well being of my football players. I have been forced into this situation without being afforded any process," he said. "Not being allowed to coach immediately will cause irreparable harm because preparation for the game is ongoing and it will be over on January 2, 2009. Every minute of preparation is critical to be ready for the game."
James was injured Dec. 16 and the next day was diagnosed with a concussion by team doctors, the person close to James said.
According to that person with direct knowledge of the situation, the player was sequestered at two consecutive practices:
— On Dec. 17, James said Leach told trainers to put him "the darkest place you can find." James was sent to an equipment shed near the practice field, where a member of the athletic staff checked on James to make sure he did not lean against anything or sit on the floor. James said Leach told him that if he came out he would be kicked off the team.
— When the team returned to practice two days later, on Dec. 19, James said Leach told trainers to "find the tightest, darkest place" for the player. James, in his street clothes, was put in an electrical closet inside the football stadium for hours, again monitored by a member of the athletic staff.
The person close to the inquiry said James spent two hours Dec. 17 in a shed the size of a one-car garage that was filled with coolers and the player was "caught" sitting down on one. All the coolers were removed, the person said, and the door to the shed was closed with James inside.
On Dec. 19, James was taken to an electrical room but the buzz was too loud, so he was taken to a press room where all the furniture was removed and he was told not to sit down, the person said.
The person close to the inquiry said Craig James called to report the allegations on Dec. 19; a university attorney interviewed him and his son Dec. 20; Leach was questioned Dec. 20 or 21; and trainers, student trainers and the doctor who examined Adam James also were interviewed.
Jerry Turner, vice chairman of the university system's board of regents, said the investigation is being handled by the school president's office, with the assistance of its general counsel and athletic director Gerald Myers.
The NCAA is letting Texas Tech conduct its investigation and has not gotten involved, NCAA spokesman Cameron Schuh said. The Big 12 has no authority to investigate what the conference labeled an "institutional matter," Big 12 spokesman Bob Burda said.
Tech is the second Big 12 school to launch an internal investigation into a coach's treatment of his players.
On Nov. 16, Kansas investigated Mark Mangino, who was the national coach of the year and got a big raise when he went 12-1 in 2007. Players said he was insensitive, though others defended him.
Mangino resigned Dec. 3 after reaching a settlement with the school that was later disclosed as a $3 million buyout.