Bonucci, 36, who spent 12 years in Turin over two spells, was left out of Allegri’s squad for the United States preseason tour and home friendlies prior to their Serie A opener on Aug. 20.
He agreed to terminate his contract with Juve to facilitate the move to the Bundesliga side Union Berlin, with whom he signed for one year on the deadline day.
“I have decided, after great suffering, to take the path of a lawsuit towards Juventus,” Bonucci told Sport Mediaset in an interview published on Thursday.
“My rights stipulated that I should have trained with the team regardless of the technical choice and been put in a position to physically be able to play during the following season.
“This was not granted to me, I no longer trained with the team. I felt drained of everything, humiliated, I couldn’t do what I love most.”
Bonucci said he did not feel remorse towards his former club nor was seeking financial reward, and that if he won the legal battle he would donate all the proceeds to charity.
“I have nothing against Juventus. Juventus are the fans, the team, my former teammates,” Bonucci said.
“I am pursuing this cause because the people who were supposed to let me end my career with Juventus in a respectful and worthy way have not done so.”
Bonucci had announced in May of this year that he would retire from football in June 2024 following the scheduled expiration of his Juventus contract.
Being sidelined from training for an extended time resulted in Bonucci not being called up for Italy this month by new manager Luciano Spalletti, who had informed the defender of his decision privately prior to making his list official.
“I want to continue to play and trouble Spalletti for the national team,” Bonucci said.
“His phone call to tell me that he wouldn’t call me up for these last games…, it was a gesture that I appreciated a lot, it shows his human depth, his sincerity.
“Not having had a proper preseason, he couldn’t call me up for the Azzurri. I expected it, I’m no fool. But I feel the national team shirt on my skin like the Juventus one. I’ll do everything I can to wear it.”
Bonucci added his hopes are to be back at Juventus one day as coach.
“When I decide to start coaching, I have my path well in mind,” he said.
“Surely Juventus, when I become a coach, will not be the one of today and maybe there will be a way, one day, to re-embrace the fans, to greet them and make them understand how important Juventus was for me. The one of today I don’t feel is mine.”
Juventus could not immediately be reached for comment.