Trial of Makarov Dreyar is an event that takes place during the Phantom Lord arc.
Following their return from Galuna Island, Team Natsu finds their guild in tatters, causing them to wonder who could have done such a thing, to which they soon find out that it was their rival guild, Phantom Lord. Although Makarov initially dismisses the attack, wishing not to fight, his mind quickly changes when he finds the now-grievously wounded Team Shadow Gear dangling from a tree in the nearby park. Enraged, Makarov declares war on Phantom Lord.
Fairy Tail then proceeds to invade Phantom Lord's guild building, and a large-scale brawl ensues; concurrently, Lucy is captured by Element 4 members Juvia Lockser and Sol. However, when Makarov goes to confront their Guild Master, Jose Porla he is tricked and has his Magic Power stolen by Aria, leaving him utterly helpless and incapacitated. Such an occurrence lowers Fairy Tail's battle strength and morale, forcing them to retreat.
Natsu then proceeds to run to Phantom Lord's Headquarters, and successfully saves Lucy. After bringing her back to the guild, Jose attacks Fairy Tail, aiming to steal Lucy back at any and all costs.
Another battle between Fairy Tail and Phantom Lord then ensues, with several of Fairy Tail's strongest members going to confront Phantom Lord's strongest team: the Element 4. Ultimately, however, the members of Fairy Tail defeat the Element 4. Natsu then motions to confront Phantom Lord's resident Dragon Slayer, Gajeel Redfox, who is torturing the recaptured Lucy, and Erza battles with Jose Porla himself.
After a long battle, Natsu defeats Gajeel and destroys Phantom Lord's Headquarters. Meanwhile, below, Erza is nearly killed by Jose, but is saved by a fully-rejuvenated Makarov, who has come to seek vengeance on Jose for harming his "children". Makarov and Jose then clash, until Makarov casts his Ultimate Magic: Fairy Law, defeating Jose and effectively ending the Fairy Tail-Phantom Lord War.
Makarov is later summoned to the Magic Council Fiore Branch Building, where he is put on trial for the war between guilds. However, during the course of the trial, he falls asleep, severely angering many of those present, save for Siegrain and Ultear, who find his actions humorous. Afterword, despite the demand for Fairy Tail's disbandment being ten times greater than it ever was, Fairy Tail is vindicated, thanks to the efforts of Yajima, and Jose Porla is stripped of his title as a Ten Wizard Saint.
Following the trial, Makarov and Yajima sit outside the courtroom, where Yajima tells Makarov that he should be grateful to him, as he helped vindicate Fairy Tail. Makarov gives Yajima his thanks, and invites him to visit the guild once it is rebuilt, where he will then treat him to ramen. Yajima demands twelve slices of pork in his ramen, but Makarov states the twelve is too much. Yajima then harshly reminds Makarov that Fairy Tail broke nearly every rule and regulation from the fourth one onwards. Hearing this, Makarov, annoyed, states that he'll give Yajima twenty, or even thirty slices of pork if he desires, but Yajima states that twelve will suffice.
Yajima then warns Makarov not to be reckless, as even other Council members, such as Org and Michello are pushing for Fairy Tail to disband. Makarov then silently stares at Yajima as he states that he should retire, and think more about himself for a change.
Later, as the moon rises, Makarov contemplates about who should be the next Master of Fairy Tail if he is to retire. For a moment, he considers his grandson, Laxus, but decides that his methodology makes him unsuited for the position. Makarov then considers Mystogan, but begrudgingly decides that he is too reclusive for such a deep-rooted position. Running out of ideas, Makarov even begins to think of Erza as a suitable candidate, but quickly rejects the idea, as she is too young. Suddenly, his train of thought is interrupted by Mirajane, who informs Makarov that Team Natsu destroyed half a stretch of road during the completion of their latest job, and that the Magic Council demands financial compensation. Mortified, Makarov dejectedly screams into the night, wondering how he's supposed to retire.