LUBBOCK, Texas(AP) Attorneys for Texas Tech University said in documents filed Tuesday that they want four school employees dismissed from former football coach Mike Leach's lawsuit over his firing and argued again that the school is immune from the suit.

It was the final day court filings could be made before a May 14 hearing on Tech's claim of sovereign immunity, which means a state agency or entity can't be sued without permission from the Texas Legislature or without a waiver based on a defendant's conduct.

"I feel we are on solid legislative ground on sovereign immunity," Tech attorney Dicky Grigg told The Associated Press.

Leach was fired Dec. 30, two days after he was suspended following a claim from the family of receiver Adam James that the coach mistreated the player after he got a concussion.

Adam James, the son of former NFL player and ESPN analyst Craig James, has said his coach twice ordered him to stand for hours while confined in a dark place during practice.

Leach, who is now living in Key West, Fla., has denied that he mistreated James and has said he suspects an $800,000 bonus he was to have received Dec. 31 was the reason he was fired one day earlier.

Leach's lawsuit includes allegations of libel and slander and breach of contract. It also accuses several top school administrators and members of the board of regents of conspiring to have Leach dismissed.

The school is seeking to have Tech Chancellor Kent Hance, university president Guy Bailey, athletic director Gerald Myers and a Tech attorney dismissed from the case. The filing did not seek to remove Craig James or two regents, all of whom were named as defendants by Leach's legal team.

Leach attorney Paul Dobrowsky said only some of the claims against the individuals could be stricken from the suit by the judge. Others, like libel, slander and conspiracy "are still viable as to the individuals."

Tech included several affidavits in its filing Tuesday. Some came from Tech trainers and Bailey, who has given his deposition in the case, also made a sworn statement.

One also came from Dr. Robert Cantu, a Boston neurosurgeon who has served on the NFL's concussion committee. In his sworn statement, Cantu says Leach should not have placed Adam James in a darkened space.

"Whereas standing alone would not be harmful, standing in a totally darkened environment with symptoms of dizziness and difficulty with balance placed Adam at risk of falling," he said. "Balance can be dramatically worsened by losing visual orientation, such as by closing one's eyes or by being in the dark."

His affidavit also states that Leach's treatment of Adam James was "unconscionable."

Dobrowsky said it was "exactly wrong" that Leach treated Adam James as if he did not have a concussion. Leach didn't want the player to "exert himself and be exposed to other potential harm," the Houston lawyer said.

"At all times Mike treated it as a concussion," Dobrowsky said.