The mother of a British student who is facing extradition to the United States over alleged copyright offences online has spoken of her anguish that he could face a possible jail sentence.

In a case carrying echoes of that of Gary McKinnon, the computer hacker who has spent years fighting US extradition, 23-year-old undergraduate Richard O'Dwyer was arrested late last month at the request of the US immigration and customs enforcement department.

Until last year, when police and US officials first visited him at his student accommodation in Sheffield, O'Dwyer ran a website called TVShack which provided links to other sites where users could download pirated versions of films and television shows. He appeared before magistrates in the capital this week for a preliminary hearing into the planned extradition, which he is fighting.

The case seemed "beyond belief", said O'Dwyer's mother, Julia, from Chesterfield. "The first he knew about it was this visit from the police and the American officials in November," she said. "He shut the website down the very next day and I don't think he expected it to go this far. But then in May he even had to spend a night in Wandsworth prison as the court was too slow for us to sort out his passport and bail.

"Richard's still studying in Sheffield. He's doing his best not to think about it. But it's a real strain for the family. I wake up every morning and think about it. What we can do? I'm no expert but I've read the extradition treaty from cover to cover."

It is the UK's 2003 extradition agreement with the US, campaigners say, which is at the centre of the problem. Much criticised in the case of McKinnon, it currently contains no provision for what is known legally as forum, which would allow a UK judge to consider whether a case is best heard in the UK or abroad.

O'Dwyer's mother says she is baffled why a case with no direct links to the US – her son last went there aged five – should be heard in the US. Her lawyers agree.

"The (computer) server was not based in the US at all," O'Dwyer's barrister, Ben Cooper, who has also been heavily involved in the McKinnon case, told Tuesday's hearing at Westminster magistrates court. "Mr O'Dwyer did not have copyrighted material on his website; he simply provided a link. The essential contention is that the correct forum for this trial is in fact here in Britain, where he was at all times."

Some experts on digital law question whether providing links to illegal downloads rather than directly hosting them would even constitute an offence in the UK. In February last year charges involving fraud and copyright against a similar site, TV-Links, were dismissed after a judge ruled that linking alone was not illegal.

"If it's an offence under UK law, then it has to be prosecuted and tested under UK law," said James Firth of the Open Digital Policy Organisation thinktank. "If there is no offence under UK law, then there is no 'victim' to copyright infringement and no case for extradition."

Civil liberties groups have also questioned why the government has not swiftly amended the extradition law by enacting a pre-existing but dormant forum clause, given that both coalition parties were heavily critical of it while in opposition. In September last year the home secretary, Theresa May, instead ordered a wider, year-long review of all extradition laws.

"The government hasn't acted in time. This is exactly what we warned against," said Isabella Sankey, director of policy for Liberty. "Enacting the forum amendment would have been quite simple. It's not that we're arguing that in every case where activity has taken place here we shouldn't allow people to be extradited. But we should at least be leaving our judges some discretion to look at the circumstances."