Jack Edward Soloff was a senior partner at Pearson Specter Litt, and the head of the firm's compensation committee.
Jack makes his first appearance in the second episode of season 5, Compensation, where he is waiting outside the office of Louis Litt. He proposes that as the new head of the compensation committee, the compensation formula should be altered. Doing this would affect the salary of Harvey Specter and because of this, Louis rejects Jack's proposal, whilst also figuring out Jack's intention of doing this only so he could pick a fight with Harvey. He also realized Jack was only doing this to try and make a name for himself at the firm.
Although Louis initially refuses to allow Jack from mentioning his proposal to anyone, he later accepts and tells him to bring it up at the next senior partner meeting, in which Jessica would be absent. Unbeknownst to Jack, Louis only agreed to let him bring it up so he could "smack it down" and show Harvey that he was on his side. Unfortunately for Louis, this plan backfired and he only ended up being scolded by Harvey, while also angering Jack in the process.
After Louis and Harvey had yet another falling out, Louis put Harvey's income sheet in the photocopier so Jack could make copies and distribute them around the firm. Once the other partners found out exactly how much Harvey made, Jack won the majority of the votes and the compensation formula was changed, causing Harvey to lose thousands if not a million off his salary.
Louis, in an attempt to get Harvey's trust back, asks Jack Soloff to overturn the compensation formula, but Jack disagrees. Louis ends up creating a new by-law and tells Jessica Pearson that the new proposed formula contradicts a by-law, but Jessica is aware that the by-law was newly made, and tells Louis it can't be done. However, Jessica later tells Jack that because of a by-law (a by-law Louis just created), his compensation formula will be reverted back to the original, and Jack gets the blame for exposing Harvey's income statements.
Sometime later, Mike Ross and Louis work on solving an issue for McKernon Motors and Dominic Barone, which involves closing a handshake deal for Dominic to buy another company within two weeks. Mike agrees to streamline the due diligence and get it done, although Louis disagrees, saying that the reason they put a time clock on the deal is so they can slip something by him. Mike finds out that the EPA is investigating the battery engine company Dominic Barone wants to buy, and so he finds an alternative - a company owned by a man named Tanaka, who is in fact a client of Pearson Specter Litt, albeit represented by none other than Jack Soloff.
Mike and Louis go to Jack for help in having his client sell his company to McKernon, with Mike enticing him with the fact that with contingent compensation restored, Jack would get 50% of the profit for himself. Jack demands 100% of the deal or nothing, and Louis relents. After Louis caters to Tanaka's Japanese culture, Tanaka agrees to sell his company to McKernon, and so Mike heads to his office to call Dominic, only to find Dominic there. Dominic is furious with them, as he tells them his friend revoked the deal when he found out that McKernon was looking into other companies as well. Mike tries to tell him that it's alright, as they found him another company, one which was better, but Louis, unaware that Dominic is in the room, comes in and announces that Tanaka pulled the deal, which causes them to be fired by McKernon.
Louis and Mike find out that Jack had instructed his client to revoke the deal in order to stab Louis in the back, because of how Louis had done the same to him. Louis and Mike head down to McKernon Motors and explain what happened to Dominic, and get rehired; however, they are told by Jessica upon returning that they have to drop McKernon as Jack had just signed Fletcher Engines, a company with three times the profit as McKernon. Louis and Mike convince Jessica that the reason they had been fired from McKernon is because Jack had sabotaged a deal, and Jessica goes to Jack's office, telling him to drop Fletcher Engines, or else she will. Jack refuses to, citing that Fletcher is way more profitable than McKernon, and tells her that if she drops them, she'd be announcing to the firm that Harvey Specter is more important to her than the other partners, or her firm as a whole, since McKernon was the first business Harvey brought to the firm, and a company Harvey is very loyal about. Jessica, however, threatens to fire him if he steps out of line again, revealing to him that she knows he's working with Daniel Hardman, who in fact gave Jack the idea to sabotage a deal with McKernon Motors and sign Fletcher Engines.
In an attempt to gain Jessica's respect, Jack goes to Mike with help on a case, although Mike refuses to work with someone he can't trust, still resenting him for causing McKernon to temporarily fire them. Jessica orders Mike to work with Jack anyway, telling him that if she were to fire everyone who stuck it to her, Mike would be first in line. Mike agrees to work with Jack on a case, but Jack thinks they should settle while Mike believes they should bring it to trial. When they go to a judge, the judge grants a trial hearing in three weeks; to make matters worse, the opposing council adds that his wife is undergoing a C-section on that very date, and demands the trial be expedited to another month, and the judge agrees. Needing access to their emails to implicate them, Jack asks for the emails within the week with the promise that they won't be charged criminally, and the opposing council agrees to hand them in the next day. Mike is furious, as the threat of prison gave him leverage, and Jack gave it away. Jack, however, asks Mike to trust him.
Mike then hands Jack a stack of papers, which he claims are emails that the opposing council tried to destroy. Although Jack had promised them they wouldn't be charged for selling false securities, they can be jailed for destruction of evidence. Jack, however, asks where Mike got the emails from, adding that if he obtained them illegally they cannot be used in court. Mike replies that he got them legally, but doesn't tell Jack where he got them from, and simply asks Jack to trust him, the way Jack had asked him before.
The pair set up a meeting with the opposing council, with them ready to settle. Mike, however, tells them that this won't be a settlement meeting for their securities fraud, but rather, for destruction of evidence. Mike produces the stack of emails, which he claims were from the company's analysts laughing about how they're ripping their customers off, and other from their CEO. The opposing lawyer immediately tells them that the emails couldn't have been obtained legally, and Mike tells them he did obtain them illegally. This pisses Jack off, who yells at Mike for lying to him, but Mike once again asks Jack to trust him. Mike then tell the opposing council that he could get all these emails legally by the time they go to court in a month, Jack adding that they could simply get emails from all of their employees by promising them immunity from being prosecuted. The opposing council surrenders, and settles, with the deal including the company's CEO to be fired.
Jack later approaches Mike and asks him how come Mike lied to him about the emails being legal. Mike reveals to him that there was no incriminating emails, and that he typed up every single one. Mike shows his laptop to Jack, and adds that he lied to Jack in order to sell Jack's reaction to the other side, telling him that the only way they would have believed the emails to be real is if they believed they were obtained illegally. Jack is impressed with Mike's tactic, calling him the real deal, and nominates him for partnership.
Jack also cuts ties with Daniel Hardman, telling him that he's got Jessica's respect now and that he no longer wishes to be associated with him.
After Mike pleads guilty to committing fraud, Jack is offered a job by Robert Zane, who is aware that the floodgates at Pearson Specter Litt will open, and that clients, associates and partners will flee. Jack gives Jessica his letter of resignation. Although Jessica tries to keep him at PSL by bringing up the legal indiscretion that he shared with her, the one that Hardman was using to blackmail him, Jack simply states that it was a full-out crime and that if she were to use that, she'd be exposing to the world that two crimes were committed by partners in her own firm, under her management. With that being said, Jack departs from the firm.