Jonathan Keogh's legal team is seeking to have CCTV footage excluded from his trial for the murder of Gareth Hutch - because they claim it was illegally obtained and breaches his right to privacy.
Sean Guerin SC, for Mr Keogh, told the Special Criminal Court that CCTV in the north inner city was "so extensive and so pervasive" that it amounted to a "significant interference" in a person's private life.
However, prosecutor Paul Burns SC said an individual could not claim privacy rights to stop themselves being investigated for an offence, in this case, one of murder.
The arguments were made as part of a voir dire - or 'trial within a trial' - to help the judges determine the admissibility of CCTV evidence.
The State is seeking to submit CCTV evidence allegedly showing the movements of the three accused in the days leading up to Mr Hutch's murder.
Mr Keogh (32), his sister Regina Keogh (41) and friend Thomas Fox (31) have denied Mr Hutch's murder.
Mr Hutch (36), a nephew of Gerry 'The Monk' Hutch, was shot dead outside Avondale House flats, on North Cumberland Street, on May 24, 2016.
In his submission, Mr Guerin argued that CCTV had been obtained in breach of his client's privacy rights under the EU Charter of Fundamental Rights.
Mr Guerin said his complaint was that, in Irish law, gardai were able to collect CCTV without "any qualification or restriction", and he argued such a system could not be said to be in accordance with law.
In response, Mr Burns said the privacy argument was being made without any reference to other competing rights.
"Where is Gareth Hutch's right to have his life vindicated?" he asked. "Where is the right of society to investigate a crime?"
The court will rule on the matter today.
It is the prosecution case that Mr Fox, of Rutland Court, and Ms Keogh, of Avondale House, both Dublin 1, were instrumental in planning the murder, and Mr Keogh, of Gloucester Place, Dublin 1, and 'Mr AB' were the shooters. The trial continues.