Courts 'could target' Twitter UK
Twitter's decision to open a UK office could leave it more vulnerable to prosecution over what its users write.
Lawyers who spoke to the BBC agreed that the move meant the company may no longer be able to claim to be solely US-based and immune to English law.
The micro-blogging site is the subject of a High Court legal challenge in relation to the naming of a footballer who had obtained a privacy injunction.
Twitter has so far declined to comment on the case.
Until recently, Twitter's operations were largely confined to Silicon Valley in California.
Last month, the company began advertising for staff to work at new European headquarters in London.
Among the posts on offer are Account Executive and Communications Manager.
Many legal experts believe that having a physical presence in the country would potentially expose Twitter to local sanctions.
Kim Walker, a partner at law firm Pinsent Masons said: "Opening an office in the UK would unquestionably make Twitter more vulnerable to lawsuits.
"The law enforcement authorities would be able to argue that it is Twitter UK which has been involved in the contempt of court or which has published the defamatory statement, so is directly responsible for the misdeed."
Mr Walker suggested that the company could claim its UK office existed for specific purposes, such as sales and marketing, and was not directly involved with the business of tweeting.
However, he warned that the argument might not convince the courts.
"If Twitter has any assets in the UK - assets in this instance is a fairly loose term, and covers staff as well as buildings and equipment - then those would be at risk if it chose not to obey rulings imposed upon it by the High Court."
That view was echoed by Simon McAleese, a defamation lawyer based in Dublin, where many US technology companies have their European headquarters.
"It is back to the very basic rule that possession is nine-tenths of the law and if you have possessions and staff then you are going to be very vulnerable to the laws of that jurisdiction," he told BBC News.
The exact nature of Twitter's London office, as well as the number of staff, is not yet known.
Industry insiders told the BBC that while lawyers may have strong views on the matter, it would take a test case to properly establish the law's authority.
They also pointed out that, although UK injunctions do not apply in the United States, individuals who feel they have been defamed are free to raise a legal action in the American courts.
Even among those lawyers who believe the law is clear-cut, there was doubt that a real-world action would be straightforward.
"Twitter would say their site operates in the States and they are simply facilitating access," said Paul Tweed, a senior partner at Johnson's Solicitors.
Mr Tweed suggested that internet companies, operating in the UK, might seek to limit their potential liability by leasing rather than buying property and limiting staff numbers.
He warned that similar cases would continue to appear if the issue of internet jurisdiction was not addressed at a higher level.
"We have to get some sort of international arbitration set up which the Americans would need to be involved in," said Mr Tweed.
Twitter was unavailable to comment on the story at the time of writing.