According to Ben Fischer of Sports Business Journal, the filing noted that McMahon fired Luck for "gross neglect" of his job early in the coronavirus pandemic, the signing of wide receiver Antonio Callaway despite the league's policy against signing players with legal issues and personal use of an XFL-issued iPhone.
Last month, Luck filed a wrongful termination lawsuit against McMahon after he was fired on April 9. Luck claimed he was fired without cause, but McMahon's lawyer, Jerry McDevitt, said Luck was informed of the reasons in a letter.
Luck was fired one day before the XFL officially suspended operations because of the COVID-19 outbreak.
After suspending operations and laying off its staff, the XFL filed for Chapter 11 bankruptcy. As a result, McMahon's attempt to revive the XFL came to an end after less than one season.
Per ESPN's Kevin Seifert, Luck was hired as the league's commissioner in May 2018 to a deal that was reportedly worth $20 million. In his lawsuit against McMahon, Luck is seeking unspecified damages.
The original XFL ran for one season in 2001 before folding, but McMahon tried to bring it back this year. The league started promisingly and many of its rule changes were widely praised, but the coronavirus pandemic forced play to be halted after five weeks and the decision was made to close it down.
One of the reasons for Luck's firing mentioned in the filing—the signing of Callaway—didn't have much of an impact on the league since a leg injury landed him on injured reserve and prevented him from appearing in any games for the Tampa Bay Vipers.
Before signing with the XFL, Callaway spent parts of two seasons with the NFL's Cleveland Browns after they selected him in the fourth round of the 2018 NFL draft out of Florida.
Callaway showed promise as a rookie with 43 receptions for 586 yards and five touchdowns, but his second year was cut short after just four games when he was suspended 10 weeks for violating the NFL's policy on substances of abuse.
Also, during his collegiate playing days at the University of Florida, Callaway was accused of sexual assault. Callaway was found not responsible in a Title IX hearing.
Luck's hiring as XFL commissioner was viewed as a coup for the league due to his experience at all levels of football. Luck, who is the father of former Indianapolis Colts quarterback Andrew Luck, spent five seasons in the NFL as a quarterback for the Houston Oilers.
He later went on to serve as the president of NFL Europe and was the NCAA's executive vice president for regulatory affairs from 2014-18.
Per Fischer, Luck's lawyers said they will issue a statement regarding McMahon's filing on Wednesday.