The High Court blocked the extradition of Lauri Love, from Suffolk to the United States remaining yr.
Mr. Love, 34, is alleged to have stolen facts from US agencies.
He changed into arrested and gadgets have been seized by way of British police. Although he changed into charged in the US, he faces no costs within the UK.
On Monday, Mr. Love, who has British-Finnish nationality, is taking the National Crime Agency (NCA) to court.
The case is being heard at Hendon Magistrates’ Court in London.
In 2015, the NCA stated it turned into refusing handy returned Mr. Love’s computer systems till he helped them decrypt a number of the files.
Mr. Love, of Stradishall, stated that, because the “NCA has not elected to pursue expenses and has seemingly now not placed any efforts into this stop”, it is time they lack the assets to him.
He said he became concerned at the “absurdly protracted” duration of time that he has had to look forward to a decision of the case.
Mr. Love, who was arrested in 2013 on suspicion of Computer Misuse Act offences, stated it was crucial to “withstand” moves that result in the “arbitrary deprivation of assets and statistics”.
The NCA said the research continued and a spokeswoman introduced: “A range of devices were seized through the NCA at the time, and those devices continue to be within the arms of the NCA.”
Mr. Love allegedly stole information from US corporations, which includes the Federal Reserve, the United States Army, the protection branch, Nasa and the FBI, in a spate of online assaults in 2012 and 2013.