The purge initiated by Elon Musk at Twitter when he took over the company left more than half of its 7,500 employees on the sidelines and now many of them are taking the SpaceX and Tesla tycoon to court.

The social media giant is facing a growing number of cases over the terms of those terminations -- and even a complaint to the city of San Francisco that Musk has illegally converted office space into bedrooms so that workers can sleep on site.

"It's very concerning that the richest man in the world thinks that he can walk all over employee rights and doesn't have to follow the law. We intend to hold him accountable," said lawyer Shannon Liss-Riordan.

Liss-Riordan is leading one such case against Twitter -- at its core, it argues that some employees are not receiving the severance and compensation promised to them prior to Musk's takeover.

These assurances, which included bonuses and stock options, were made to keep employees at Twitter, guaranteeing an exit package as the arrival of the mercurial Musk loomed.

Other cases are taking Musk to task over his brash ultimatum that staff either sign up to his vision for the company and embrace a "hardcore" work ethic, or take three months of their salary and quit.

This, lawyers allege, was a disguised layoff plan that ignored California law by denying workers the compensation and 60-day warning time required by law.

- 'Blunt disregard' -
Musk's disdain for working from home is also being resisted, with employees with disabilities or health concerns seeing orders to come back to the office as discriminatory.

"There was a blunt disregard for personal conditions such as relevant medical issues. All this was done while Elon Musk was abusing us in public on Twitter," said a former senior employee at Twitter, Amir Shevat.

Shevat and other employees are represented by Lisa Bloom, a high-profile attorney in Los Angeles who has represented disgraced Hollywood producer Harvey Weinstein.

Bloom is handling arbitration claims since many Twitter employees signed away their right to fight their plight in court when they joined the company.

"We will continue to file these claims, one by one, bombarding Twitter with claims," Bloom told a press conference on Monday.

"We are prepared to bring hundreds if not thousands of individual arbitrations to make sure that the employees get what they're owed," she said.

This, experts said, could cost Twitter and Musk dearly.

Twitter "could quickly resolve the matter by paying the ex-employees whatever they are entitled to under the law," said Eric Goldman, a law professor at Santa Clara University.

"Or it could play hardball and make them work for it, which could take years," he said.

The stack of legal cases could also force Musk to work towards a settlement, especially since his company is under huge financial stress after he paid $44 billion to take full ownership.

The usually outspoken entrepreneur has said little specifically about legal cases, reserving criticism for a city inspection after Twitter conference rooms were converted into makeshift bedrooms.

"So city of San Francisco attacks companies providing beds for tired employees instead of making sure kids are safe from fentanyl," Musk said in a tweet, lashing out at Mayor London Breed.

Musk was referring to a recent scandal of a 10-month-old boy who overdosed on fentanyl after ingesting the substance at a playground.