Lawyers representing Graham Dwyer have told the High Court there are no independent oversights when State entities seek data from mobile phone service providers when investigating serious crimes.

Remy Farrell, Senior Counsel for Dwyer, told Mr Justice Tony O'Connor that, under the 2011 Communications Act, once a senior officer of An Garda Síochána, a colonel in the Defence Forces, or senior officials with Competition Authority and the Revenue Commissioner make a request for data, the service providers are obliged to hand over the information sought.

The act does not provide for any independent person, such as a judge, to oversee such requests, to limit what is strictly necessary or ensure privacy rights are protected, Mr Farrell said.

It would appear that the only people who had oversight of the request in relation to his client were the gardaí themselves, he said.

The lack of an independent oversight is one of the grounds advanced by Dwyer in his claim that certain provisions of the 2011 act breach his privacy rights under the European Charter, Irish Constitution and rights under the European Convention on Human Rights.

In 2014, the European Court of Justice found a 2006 EU directive concerning data retention to be invalid.

Dwyer claims that the 2011 act was introduced by the State to give effect to the 2006 directive, and that it also suffers from the same flaws identified by the ECJ.

Evidence gathered under the 2011 act should not have been used against him in his trial, Dwyer claims.

Mr Farrell was speaking on the second day of Dwyer's challenge against the Garda Commissioner and the State over the retention of data from mobile phones.

In 2015, Dwyer was sentenced to life imprisonment after the jury found him guilty murdering childcare worker Elaine O'Hara.

He denies killing Ms O'Hara, and has challenged provisions of the 2011 act, which allowed gardaí investigating her death obtain and use mobile phone records during his lengthy trial.

His appeal against his conviction remains pending before the Court of Appeal.

Mr Farrell commented about the lack of an independent oversight when reading extracts of the transcript of Dwyer's trial at the Central Criminal Court, including details of Dwyer's application that certain prosecution evidence be excluded, based on the 2014 ECJ ruling.

That application was dismissed by the trial judge Mr Justice Tony Hunt.

Mr Justice O'Connor also heard questions concerning the background of the case and details of what were put before the Central Criminal Court in 2015 to Dwyer's solicitor Jonathan Dunphy by Sean Guerin SC for the State respondents and the Garda Commissioner.