Harry gasps. The courtroom is the same one he saw in Dumbledore's Pensieve last year, and it's filled with about fifty people. A man tells Harry he's late and that it's Harry's fault for not getting the memo as Harry takes his seat. Harry looks around and sees Fudge with a woman he suspects is Amelia Bones and another woman in shadow on his other side. Percy is there to take notes and acts like he doesn’t recognize Harry. Fudge begins the hearing just as Dumbledore walks into the room, saying that he's a witness for Harry. Harry feels hopeful and tries to catch Dumbledore's eye, but Dumbledore stares at Fudge.
Notice how badly Harry wants Dumbledore to acknowledge him—Harry wants to feel as though Dumbledore is actually on his side, and Dumbledore's odd choice to ignore Harry makes Harry feel alone, despite the fact that Dumbledore has clearly come to his defense. At the same time, however, Harry understands that Fudge can't steamroller him as effectively with Dumbledore there, which shows that Harry still trusts Dumbledore and expects him to take care of things. With the armchair, Dumbledore makes the very serious affair of the trial seem ridiculous—and it is, given that Fudge has called the same assembly that usually judges Death Eaters to judge the trivial crime of an underage student using magic.
Dumbledore conjures himself a chintz armchair as Fudge starts to read Harry's crime. Fudge looks flustered but begins to question Harry. He only allows Harry to answer yes or no to questions, though Amelia Bones cuts in to confirm that Harry can conjure a true Patronus. She's impressed. Harry says he did it because of the dementors, which makes the people in the courtroom go silent. This piques Amelia Bones's interest and she seems to take seriously the fact that dementors were in a Muggle town, but Fudge says that Harry's lying. Dumbledore cuts in that he brought a witness. Percy shows Mrs. Figg into the courtroom.
Remember in the previous novel that Dumbledore suggested that the dementors would abandon the Ministry and join Voldemort. This is likely why Fudge refuses to believe that the dementors could be out of his control, as that would mean accepting that Dumbledore was right. In doing so, Fudge shows that he prioritizes keeping his own power over keeping everyone else in the world—not just the Wizarding world—safe.
Mrs. Figg says she's a Squib, and when Fudge asks with derision if Squibs can see dementors, she indignantly insists they can. She gives her version of the story and though she describes the dementors' appearance poorly, she perfectly describes the way dementors make a person feel cold and hopeless. Fudge dismisses Mrs. Figg and declares she wasn't a convincing witness. Amelia Bones is still concerned that there are rogue dementors, but Dumbledore calmly says that someone ordered the dementors there. The witch next to Fudge, introduced as Dolores Umbridge, leans forward and asks Dumbledore to confirm if he's implying that the Ministry ordered an attack on Harry. When Dumbledore does, Fudge turns bright red.
The way that Fudge treats Mrs. Figg, both in front of her and when she's gone, suggests that Fudge believes in a hierarchy of people, just like Voldemort and Sirius's family do. Again, this reminds the reader that someone doesn't need to actually be Voldemort’s follower in order to hold views that are cruel and discriminatory. Dumbledore's choice to pick at Fudge and the Ministry shows that he's using the hearing to make his points to Fudge again, in an arena where he must be allowed to make them and be heard by others. This scene also introduces Umbridge, who becomes this book’s main antagonist other than Voldemort himself.
Fudge tries to return the subject to Harry's use of underage magic, and Dumbledore points out that according to the law, Harry was allowed to use magic to defend himself. Fudge loses his temper and says that Harry has a habit of using magic outside of school and getting into trouble in school, but Dumbledore reminds Fudge that Fudge can't expel students. Dumbledore suggests that Fudge is being unreasonable and asks him to come to a verdict. Amelia Bones calls a vote and Harry is thrilled to see that more than half vote to clear him. Fudge dismisses the courtroom and Dumbledore leaves without looking at or greeting Harry.
The way that Dumbledore is able to use the law to his advantage to clear Harry shows that with the right person in charge of the law, it can do what it's supposed to do and protect vulnerable people. Fudge, however, shows how easy it is for someone to abuse that power and remove people from society that oppose him via the court system. Again, Dumbledore’s refusal to look at Harry is presented as a mystery, though to Harry it mostly feels frustrating and isolating.