The High Court has been told new material has come to light in proceedings taken by Ian Bailey against the Garda Commissioner for wrongful arrest and personal injuries.
Mr Bailey is suing the garda authorities over their investigation into the murder of French film-maker Sophie Toscan du Plantier in 1996.
He was arrested twice in connection with the killing and has always denied any involvement.
Last year he won an appeal against his extradition to France.
He has also made a complaint to the Garda Ombudsman.
He is seeking documents from the State to support his case against the gardaí.
The High Court made orders earlier this year directing the State to hand over certain documents.
The court was told today that there has been a delay in handing over some documents.
Senior Counsel Paul O'Higgins said that the State was now in a position to allow around 16,000 documents to be inspected by lawyers for Mr Bailey.
However, he said there was a difficulty with some data which was in electronic form.
He said certain fresh and unexpected material had come up in relation to matters such as phone traffic.
However, he said this material was in an old, obsolete and fragile electronic format and was proving difficult to "unscramble".
He said gardaí had called in technical experts from within the force and from abroad to allow the material to be produced to Mr Bailey's side.
He said he had been told this would take three to four months.
Lawyers for Mr Bailey said they were concerned that they would be told in three or four months that there would be a further delay in producing the material.
Barrister Ronan Munroe said they had received documents which raised significant concerns in the context of Mr Bailey's appeal against his extradition and were anxious to get any further material as soon as possible.
Mr Justice John Hedigan gave the state until 25 March to produce the additional material.
The matter will be mentioned before the court again on 28 March.