During a high-profile career, Alan Dershowitz has defended OJ Simpson and Claus von Bülow against murder charges and advocated the use of torture against terrorism suspects.
In December Mr Dershowitz echoed US Secretary of State Hillary Clinton's claim that WikiLeaks poses a danger to the US and to international diplomacy, following the publishing of thousands of US diplomatic cables.
Now the New York lawyer has become a surprise addition to Julian Assange's defence team. Geoffrey Robertson QC, Mr Assange's head lawyer, unveiled the Harvard law professor as an adviser in his battle against the US Justice Department.
A Federal Magistrates' Court in Virginia is seeking a subpoena to obtain the personal details of anyone who used Twitter to communicate with WikiLeaks. The US is trying to build a conspiracy case that Mr Assange solicited leaks from individuals including Pte Bradley Manning, the army intelligence analyst suspected of supplying classified information.
Mr Assange, still under bail conditions in Britain as he awaits his appeal against a European arrest warrant for his extradition to Sweden on allegations of rape, will not appear in the Virginia court.
His UK legal team has called in Mr Dershowitz, described as America's "most peripatetic civil liberties lawyer" and "the top lawyer of last resort", to challenge the US Attorney General's action. Mr Dershowitz, who will serve as a legal consultant, told politico.com: "I'm currently in this case because I believe that to protect the First Amendment we need to protect new electronic media vigorously."
Twitter has indicated that it would fight the Virginia court order, claiming that it breaches its right to protect the confidentiality and free speech of its users. Mr Assange is also arguing that as an Australian citizen, the US court has no jurisdiction "over expressive activities beyond its borders".
Mr Dershowitz and Mr Assange might seem odd bedfellows. Mr Dershowitz is a passionate defender of Israel. The leaked WikiLeaks cables have embarrassed the Israeli government while Mr Assange was accused of using a known anti-Semite and Holocaust denier as WikiLeaks' Russian conduit.
Mr Dershowitz has also advocated a controversial legal position on torture. He argues that torture "warrants" could be issued in specific circumstances when it could prevent an imminent attack.
The lawyer has won 13 out of the 15 murder and attempted murder cases he has handled, the most high profile of which being the unlikely acquittal he helped secure for OJ Simpson in 1995, who was accused of murdering his estranged wife Nicole and her friend, Ronald Goldman.
Dershowitz – on the record
"The representation of a guilty and despicable defendant, with little chance of winning, is a challenge and one of the highest obligations of my profession."
"If the US President thinks it's essential to defend the lives of thousands of people, he ought to be on the line. He ought to have to sign a torture warrant saying, 'I'm taking responsibility for breaking the law, for violating treaties, for doing an extraordinary act of necessity.' "
The WikiLeaks founder, who is fighting extradition to Sweden, is the latest of many famous figures to have called on Dershowitz's legal prowess.
Dershowitz was among a team of lawyers who helped to acquit Simpson of the murder of his ex-wife Nicole Brown and her friend Ron Goldman in 1995.
One of his few courtroom defeats came in 1978 when Dershowitz failed to overturn the conviction of kidnapped heiress-turned-terrorist Patty Hearst.
Claus von Bülow
The British socialite was convicted of murdering his wife in 1982, but was later acquitted in a retrial after Dershowitz had the verdict overturned.
Dershowitz was also unsuccessful in revoking Tyson's conviction for raping Desiree Washington in 1992, but claimed a "grave injustice" had occurred.Reuse content