Twitter Inc’s sweeping job cuts, which have already led to a lawsuit in California, will also have to satisfy stringent employment regulations across Europe if its new owner wants to avoid more legal challenges.

About a week after billionaire Elon Musk took control of Twitter, workers from San Francisco to Dublin have been locked out of their work accounts, and the company circulated a memo that said all employees would be notified about their status by 9am California time on Friday.

The company has already been sued in San Francisco, although the lawyer who filed the suit later said Musk is trying to comply with the law. Musk, who plans to eliminate half of the company’s workers - some 3,700 positions - to slash costs at Twitter, won’t find the cuts any easier in Europe.

In the UK, where Twitter employed 281 people as of last year, British employers are required by law to prove there are grounds to remove workers from their jobs. If more than 20 employees are let go from a firm, the company needs to follow consultation requirements, including reporting to the government and allowing at least 30 days between starting the process and dismissal.

A representative for Twitter didn’t immediately respond to a request for comment.

Musk could take a lesson from P&O Ferries Ltd. The company, which runs ships across the English Channel, caused an uproar when it attempted to fire 800 workers on the spot earlier this year via a video message. P&O was subjected to civil and criminal probes by the UK government, some of the company’s ships were detained for safety inspections, and its chief executive officer was grilled at the House of Commons.

“Any failure to comply with these obligations before dismissing employees will result in potential claims,” Jo Keddie, a lawyer at Winckworth Sherwood, said in an interview.

Keddie said that her firm has received a “mini tsunami” of inquiries from concerned Twitter employees who were affected by the sudden action.

UK employment tribunals, which would become the country’s stage for any disputes, caps awards for unfair dismissal at around £93,000 . However, if the employee can prove discrimination then the award could be limitless.

Twitter employees in the UK have been joining trade unions in an effort to better protect their rights. Prospect, a UK-based trade union, has seen an influx of new members from Twitter over the last week, General Secretary Mike Clancy said.

Clancy on Friday requested an urgent meeting with UK business secretary Grant Shapps over what what he called the “unacceptable” manner of job cuts.

Britain’s United Tech and Allied Workers labour group condemned the way Twitter employees had been treated and said it was welcoming new members from the company.

European Union members also generally require employers to give notice if they fire a significant number of workers, which vary on a country-by-country basis.

 - Bloomberg