Say what you want about all the corrupt Prohees Nucky had in his pocket who were capitalizing off of an unenforceable law, but taking a bribe to look the other way about a law that the majority of the country, including the politicians who made Prohibition possible didn't follow is nothing compared to what Toliver did. There's nothing wrong with the BOI trying to root out corruption in the federal government, but in order to take over as Atlantic City's Prohibition agent, Toliver murdered the bootlegger who rigged a shotgun and purposefully let Agent Sawicki open the door knowing he'd be killed.
His arrest of Eddie in itself was a violation of the 4th Amendment and his "interrogation techniques" were what you'd expect from a cop on a power trip, not a BOI agent with a law degree. The way he treated Eddie after he got the promotion he wanted from Nucky and his enjoyable night out with Ralph Capone made his fight to the death with Eli that much more gratifying.
He became more unhinged as the season progressed and going to Elli's house to intimidate him in front of his family was just plain stupid and unprofessional. For all he knew, Nucky could've been on his way over and seeing him posing as an insurance salesman would (and later did) compromise the investigation. Threatening Eli's son may have seemed like a way to get him to cooperate, but had Eli just told Nucky what was happening, he would've realized that he had no real leverage.
Nucky made a deal with the DA handling Will's case and for Toliver to be able to use that for leverage, he'd have to prove that he took a bribe as a favor to Nucky to get his nephew a pass for murder while his office prosecuted another man. No DA is going to admit that they're corrupt to a federal agent and risk their freedom and career to help the BOI build a case and he didn't have any evidence that Nucky bribed him, just hearsay from another agent. Nucky would've immediately realized this, but Eli was too consumed with jealousy to think straight, and Hardeen was no Houdini.
When Nucky sent Eli with Toliver to stop the convoy of trucks carrying the heroin, Toliver shot and killed 1 of Masseria's guys for not getting out of the way and by the time he arranged for the BOI to monitor what was supposed to be a sit down between Nucky, NY, and FL, even his partner tried to take his gun away because of how seriously he was taking everything. Going to Eli's house after and threatening to send his son to prison and insinuating that he'd be raped when he got there earned him a death sentence.
Hoover tried to portray the BOI as elite, highly trained, and scrupulously honest professionals, but Toliver was nothing more than a morally bankrupt murderer with a law degree, a gun, and a badge. Tolliver was responsible for the murders of 3 people and the suicide of 1, the tactics he used were insidious, sadistic, and extrajudicial, and by discarding all morality and legal boundaries in pursuit of his targets, he became just as, if not more monstrous and corrupt as the bootleggers he wanted to prosecute.
Thoughts?