In 2010, he represented Julian Assange, the founder of WikiLeaks, defending him against an extradition request to Sweden based on suspicion of numerous sexual offences.

He went on to study European Community Law at the Vrije Universiteit in Brussels and before being admitted as a Solicitor of the Supreme Court in England and Wales in July 1982.

[2][7] In February 1991, Stephens was acting as a solicitor for the National Union of Mineworkers (NUM) when John Hendy, Geoffrey Robertson, and two other QCs defended Arthur Scargill and Peter Heathfield against claims that they had handled funds inappropriately during the miner's strike of 1984–85.

[8][9] In 1992, he worked on a case brought by the NUM against the government that saw an earlier decision to close 31 coal mines overturned after it was deemed unlawful.

[10] When allegations of an affair between James Hewitt and Diana, Princess of Wales, were published by The Sun in 1992, Stephens claimed through the Press Association he had issued proceedings against the newspaper for defamation even though he had not actually served the writ.

[13] According to The Guardian, in 1995, his public profile was further raised by defending Greenpeace against litigation brought by Shell over an alleged illegal occupation of the Brent Spar oil platform.

[14] Stephens provided pro bono assistance to two activists: Helen Steel and David Morris, who had handed out leaflets stating "What's wrong with McDonald's?"

[19] In 2008, he won an apology from a former police driver who had written "appalling lies" about the novelist and essayist Sir Salman Rushdie regarding the book The Satanic Verses.

The judges agreed with the media and ruled that the names should be released, noting that anonymity orders had become "deeply ingrained" in court cases in the UK.

Soon after the WikiLeaks cables disclosure began, Stephens told The Guardian that he thought he was being monitored by the security services and that his home was being watched.

[43][44] Stephens is currently serving on the Executive Committee of the Commonwealth Lawyers Association and was elected President of its Council at the Cape Town Conference in April 2013.

Most recently, Stephens has become a member of the legal panel of the Human Dignity Trust[50] and a trustee on the UK board of the international media development organization Internews.