A garda has been accused of lying "in a dishonest and disreputable fashion" about Solidarity TD Paul Murphy's actions on the day of a water protest in Jobstown.

Seán Guerin SC, defending Mr Murphy, suggested to Garda Gavin Cooke that he had deliberately toned down his "false" evidence in a "cowardly" way, Dublin Circuit Criminal Court heard.

Gda Cooke rejected the claims while giving evidence on day 13 of the trial of Mr Murphy, 34, and six other men.

Mr Murphy along with South Dublin Councillors Michael Murphy (53) and Kieran Mahon (39) and four other men have pleaded not guilty to falsely imprisoning Ms Burton and her advisor Karen O'Connell by restricting their personal liberty without their consent at Fortunestown Road, Jobstown, Tallaght on 15 November 2014.

The two women were attending a graduation ceremony at An Cosán adult education centre in Jobstown when anti-water charge protesters began demonstrating around them.

They were trapped in cars for about three hours, the trial has heard.

Gda Cooke was on duty on the day and the driver of the first car Ms Burton and Ms O'Connell remained in at a local church for about an hour, the trial heard.

At one point, Gda Cooke described seeing Paul Murphy on a microphone "doing different things".

Under cross-examination from Mr Guerin, he said he saw Mr Murphy directing people where to stand.

The court was then shown CCTV footage from the relevant period, which Mr Guerin said to Gda Cooke "gives the lie to your evidence".

"You weren't even in the church grounds for most of the time Mr Murphy was there," Mr Guerin said.

Gda Cooke said he did not see Mr Murphy in the CCTV footage, but said: "I'm clear as to seeing Mr Murphy that day."

"What you're telling the jury is that you saw something that couldn't have happened," Mr Guerin said.

He put it to Gda Cooke that as well as saying in his statement that Mr Murphy was directing people, he also gave evidence to that effect in another case in the District Court when Mr Murphy was not on trial.

Mr Guerin said Gda Cooke then tried to "tone down" his evidence in this trial by initially saying he saw Mr Murphy doing "different things".

"I suggest to you not only did you deliberately falsify your account of what happened, you gave false evidence in the District Court and (moved) away from your falsehood in a dishonest and disreputable fashion because you knew your statement was false," Mr Guerin said.

"That's not true," Gda Cooke replied. He said he gave a true statement and has always spoken the truth in court.

Mr Guerin said: "The reason you gave a false statement was you wanted to establish Paul Murphy was guilty of an offence. You knew his peaceful actions on the day would not be sufficient. You wanted to make him responsible for the behaviour of other people."

Gda Cooke denied this was the case.

Under questioning from prosecution barrister Tony McGillicuddy BL, Gda Cooke described how the protesters were shouting "vile" language as they surrounded the car.

He said after helping to move Ms Burton and Ms O'Connell from the car to the jeep, he saw two gardaí being assaulted by protesters.

He said he received "two boxes in the back of the head".

Paul Murphy of Kingswood Heights, Tallaght; Kieran Mahon of Holbrook Grove, Tallaght; Michael Murphy of Whitechurch Way, Ballyboden, Dublin; Frank Donaghy (71) of Alpine Rise, Tallaght; Ken Purcell (50) of Kiltalown Green, Tallaght; Michael Banks (46) of Brookview Green, Tallaght and Scott Masterson (34) of Carrigmore Drive, Tallaght have all denied the charges.

The trial continues before Judge Melanie Greally and a jury.