Image copyright AFP Image caption Reza Zarrab, an Iranian-American businessman, speaks to the media with his lawyers and Meghan Markle on Tuesday in London
What is the case?
The court heard it was an American man and British woman, who was born in Britain and is of Iranian heritage, who brought the action under the United Kingdom’s Human Rights Act.
He and her fiancé were accused of trying to extort money from Iran in exchange for the release of a detained Iranian-American businessman, Reza Zarrab.
How did the process go?
Despite many high-profile barracking sessions, no journalists were able to attend the proceedings, where a huge volume of information was being discussed.
Parties involved were called before the High Court to discuss matters regarding Iran’s role.
Mr Zarrab, who is out on bail, denies criminal conspiracy to commit money laundering and conspiracy to commit violating the US Foreign Sovereign Immunities Act.
The court heard from witnesses relating to a number of other countries.
Court proceedings were closed so the public could attend for a series of witness statements, and the Crown Prosecution Service was assisted by lawyers and caseworkers from the Foreign and Commonwealth Office and the intelligence services.
Some witnesses did attend to give evidence, including Mr Zarrab’s fiancee, who was flown in from Britain, but a number of others, including a United Nations official and a representative of the European Commission, declined to be present.
What was discussed?
The case includes allegations that Mr Zarrab and his fiancé made a video message which was circulated in their home country.
They were accused of being part of a network using bribery and blackmail to secure money for the Iranian government, and were alleged to have been trying to extort US funds using “threats of political violence and violence and the use of the threat of terrorism and intimidation”.
In addition, it is alleged that an order for the extradition of Mr Zarrab to the United States is unlawful.
Image copyright Getty Images Image caption Relatives of Mr Zarrab arrive to watch the first day of the court’s proceedings
The court heard that Ms Markle has said she was hoping to visit Mr Zarrab in prison in 2017, just days before he was arrested.
A statement released by her lawyer added that she supported the couple’s case.
What will happen now?
The hearing will run for 11 days over three weeks and will conclude on 6 May.
Once a “one-off set of proceedings” in the High Court has been completed, the matter will return to the US courts.
In the meantime, Mr Zarrab has been allowed to continue to serve his sentence in Iran.
Many other process, including attempts to extradite Mr Zarrab, have been put on hold.
Image copyright EPA Image caption The London trial of Zarrab, a former top oil trader, is due to start in April next year
What is the British case?
The case of a British national of Iranian heritage was heard at a hearing behind closed doors at the High Court.
His barrister told the court that Ms Markle was born in Britain and that he was Iranian-American.
The barrister said Ms Markle’s fiance did not have any contact with Mr Zarrab and that they had no previous “ties”.
The court was told that Ms Markle could visit Mr Zarrab once he had been released, but was not yet facing charges.