Four gardai held a woman in the bathroom of her flat while they beat her teenage son in another room, a court heard today.
Officers Alan Conlon, Claire Delaney, Eoin Murtagh and Sean O'Leary are charged with assault causing harm, forcible entry and trespass at the inner city Dublin home on February 17 2008.
All four, who are suspended from the force, were accused of entering the Basin Street flats near St James's Hospital on that Sunday afternoon without a warrant.
Dublin Circuit Criminal Court was told the gardai used a baton to beat Owen Gaffney, aged 17 at the time, and kicked and punched him.
Prosecuting barrister Tom O'Connell, senior counsel, told the court the incident appeared to be a pre-arranged plan to give Mr Gaffney a beating.
"This case is about guards behaving unlawfully for reasons which will become apparent in the course of the trial," he told the court.
Three of the accused, Conlon, Delaney and Murtagh, are also accused of false imprisonment of Mr Gaffney's mother for five minutes in the bathroom while her son, who had been in bed, was assaulted.
Judge Desmond Hogan told the four officers the trial was expected to last two weeks.
Three of the gardai, Delaney, Murtagh and O'Leary, were stationed in Kilmainham at the time and Conlon was stationed at Kevin Street.
The teenager's mother made allegations that her son had been assaulted by a number of gardai.
A complaint was later made to the Garda Ombudsman which launched an investigation.
The officers have pleaded not guilty.