A Sheffield student accused of breaching US copyright would be a "fish out of water" if he was extradited, a court has heard.
Richard O'Dwyer, 23, is fighting extradition over claims he set up a website where films and TV shows could be watched for free.
Westminster magistrates heard he would be at risk if he was to be sent to a New York federal detention centre.
Judgement on whether to extradite him was reserved until 13 January.
His lawyer Ben Cooper said if extradited, Mr O'Dwyer would face pre-trial imprisonment as a foreign national with no ties to the country.
"Mr O'Dwyer is a young man yet to complete his degree and his social environment would be removed from him.
"That is going to impact on his reaction to finding himself surrounded by the sort of people who will inhabit a federal detention centre in New York.
"He would be a fish out of water in such an environment. One cannot underestimate the risks that would pose to him."
Mr O'Dwyer faces charges of copyright infringement and conspiracy to infringe copyright over the website TVShack.
The US Government has alleged the site offered free downloading and streaming of thousands of films and television programmes without permission from the copyright holders.
Mr O'Dwyer earned money through hosting advertisements on the site, allegedly receiving more than $230,000 (£147,000) in advertising revenue since January 2008, according to the US authorities.
Mr Cooper argued the site did not store copyright material but merely pointed users to other sites where they could download films and TV shows.
The lawyer said his client would be the first UK citizen to be extradited for such an offence and he would effectively become a "guinea pig" for copyright law in the US.
John Jones, for the US authorities, told the court the victims of the alleged offences included the film studios.
He said the website highlighted the savings that could be made on cinema tickets in the US.