After Pomona emerged from her coma at Malfoy Manor, Narcissa stayed by her side throughout her recovery. During one of their conversations, Narcissa mentioned something.
Cornelius Fudge's nephew had originally worked at the Office for the Misuse of Magic. In 1999, he made a bet with someone and made an entire Muggle subway train disappear. He was investigated as a result.
Even if there had been no one aboard, it was still an entire train that had vanished, not merely a car. He was investigated afterward and suspended from the Office for the Misuse of Magic two days later.
At first, he had tried to argue his way out of it, but he had not known that Muggle subway trains had cameras. Though there were few of them, they still recorded his agile figure.
Harry had once been summoned by the Ministry of Magic simply for using Expecto Patronum in a tunnel. Fudge had made a great fuss of it, gathering all the members of the Wizengamot as though a little boy using Expecto Patronum were a major criminal like Karkaroff.
While Albus Dumbledore was still alive, although the Ministry of Magic was not subject to any formal oversight or restraint, they at least had someone to fear. Once Dumbledore died and Voldemort's Horcruxes were destroyed, making it seem impossible for him to return, they could do whatever they pleased. Even when Harry warned them that his scar still hurt, they pretended not to hear, claiming that Harry was merely seeking attention.
When Severus returned, the former Death Eaters gathered at Malfoy Manor to complain to him about all the unfair treatment they had suffered.
Looking back now, it made no sense at all. Snape was a traitor; the Death Eaters ought to have "executed" him as they had Karkaroff.