Tesla CEO Elon Musk is expected in court on Monday, and the stakes are high — if he loses he could have to pay upwards of $2 billion from his considerable personal wealth.

Musk will be the first witness in a trial to defend his role in Tesla’s $2.6 billion acquisition of SolarCity. Shareholders have sued Musk and members of the Tesla board, alleging that the 2016 deal amounted to a SolarCity bailout.

They also allege that it unfairly enriched the Musk family, who were among the largest shareholders, and that Musk and others failed to disclose all pertinent details and breached their fiduciary responsibilities. Musk has insisted he was “fully recused” from negotiations over the deal. 

Last year, the board members named in the suit settled with the Tesla shareholders for $60 million with no admission of wrongdoing. Musk, the second-richest person in the world, was the only defendant who chose to take the fight to court.

There’s no jury to persuade in this matter. His fate will be determined by the Delaware Chancery Court’s judge, Vice-Chancellor Joseph Slights III.

Musk has had his share of legal problems beyond SolarCity.

For example, the SEC sued him in 2018 for fraud, with Musk and Tesla settling, paying $20 million each. The charges came after Musk tweeted about taking Tesla private for $420 a share, a move that sent Tesla’s stock price soaring. Musk had to temporarily relinquish his chairman role at Tesla as one of the terms of the settlement.

In a separate case, he emerged victorious after caving expert Vernon Unsworth said Musk had defamed him when the Tesla CEO called him a “pedo guy” on twitter. His attorneys argued that “pedo guy” was heated rhetoric and not meant as statement of fact.

Tesla and Musk are facing many other lawsuits, including one over Musk’s unprecedented CEO compensation package, and a number of federal probes according to the company’s own financial filings.

In the SolarCity case, the judge will have to decide whether Musk was a conflicted controlling shareholder who met the “entire fairness” standard in his handling of the SolarCity acquisition.

In other words, was Musk acting in Tesla shareholders’ best interest? And did Musk tell shareholders everything they deserved to know?

Known as a shareholder derivative action, this kind of lawsuit is filed by investors on behalf of a corporation, rather than the individuals or funds themselves. If the plaintiffs win, proceeds may go to Tesla and not to the stakeholders who brought the suit.

According to a filing with the chancery court, Musk owned 22.1% of Tesla common stock at the time of the deal, and 21.9% of SolarCity. SolarCity was a troubled asset that was bleeding cash in the capital-intensive market of residential solar deployment.

Musk’s attorneys are expected to argue that the SolarCity deal hasn’t harmed shareholders at all and that they voted overwhelmingly to approve the acquisition. After all, Tesla shares have skyrocketed from a closing price of $43.92 on June 21, 2016 — when Tesla announced it would bid for SolarCity — to a closing price of $656.95 on July 9, 2021 (Friday) after a five-for-one stock split last year.

The company is also part of the S&P 500 now, and reports profits regularly.

SolarCity was founded and run by Musk’s cousins, Lyndon and Peter Rive, but backed by Musk who served as chairman of the board. Meanwhile, he also was CEO of Tesla, as well as the company’s chairman.

That wasn’t his only potential conflict. SpaceX, Musk’s aerospace venture, had invested $255 million in SolarCity bonds from March 2015 to March 2016. Four members of Tesla’s board directly or indirectly owned SolarCity stock at the time the acquisition was under consideration. And some Tesla board members also held shares in SpaceX and were on its board.

To Musk and many of his supporters, the acquisition of SolarCity in 2016 represented a natural combination of his companies and a way for Tesla to pursue its environmental mission with a broader array of products. Homeowners would be able to finance and install solar rooftop panels from the same company that provided their electric vehicle, home charging station and backup battery for energy storage.

Tesla had already launched an energy division in late 2015, with a home battery dubbed the Powerwall and other big batteries for use by businesses and utilities.

By June 2016, Musk said Tesla would bid $2.8 billion to buy SolarCity. “I don’t think this creates additional financial risk for Tesla,” he said at that time, and called a merger “blindingly obvious.” But Tesla investors were skeptical, with the stock price plunging more than 10% on the announcement. 

In July 2016, Musk presented his vision of Tesla as an automotive innovator and renewable energy titan in his famous “Master Plan Part Deux.”

As CNBC previously reported, unsealed court documents, including emails between Musk and SolarCity execs, would later reveal that he knew SolarCity was facing a “liquidity crisis” even as Tesla pursued the acquisition.

“Three things need to happen to change investor sentiment: SolarCity solving its liquidity crisis, an LOI with Panasonic to address solar cell production risk, and a joint product demo,” Musk wrote to SolarCity execs in September that year. “Should be able to do all those before the shareholder vote.”

In October 2018, Tesla and SolarCity jointly announced a combined solar roof and battery pack. Musk showed off what looked like a solar panel, miniaturized and sleek enough to be mistaken for high-end roofing materials, at the Hollywood set of Desperate Housewives. 

The hype event did help him to turn investor sentiment. In November, the deal was approved in a vote by 85% of shareholders. But after it closed, Tesla’s SolarCity business would falter.

Through the years, the company repeatedly delayed mass manufacturing its Solarglass roof tiles. The ones Musk presented as a production-ready prototype in 2016 were actually a non-functional design prototype.

Walmart sued Tesla after fires broke out on panels the company had installed atop their facilities. A former Tesla Energy employee filed a whistleblower complaint to federal agencies about the fire risks of Tesla’s solar rooftops. And Panasonic exited from the Buffalo plant that Tesla took over, once it was clear Tesla was not going to manufacture its solar roof tiles there.

While the Tesla solar roof tiles have not taken off, the company’s energy storage products are on a tear, as demand for lower-cost electricity from renewable sources picks up worldwide.

In the trial starting Monday in Wilmington, Delaware, Musk will be represented by attorneys with Ross Aronstam & Moritz (David E. Ross, Garrett B. Moritz and Benjamin Z. Grossberg). The trial is expected to run until July 23, 2021, unless the entities seek a settlement before it’s done.