A magistrate allegedly groomed a boy for years before he molested him at his home and on a sailing trip around Sydney Harbour, a court has heard.

Key points: Magistrate Graeme Curran is on trial accused of molesting a young boy several times

Magistrate Graeme Curran is on trial accused of molesting a young boy several times The boy regarded the accused as part of the family, the court hears

The boy regarded the accused as part of the family, the court hears The defendant's lawyers will argue the allegations are false and the boy is "mixed up"

High-profile Sydney Magistrate Graeme Curran is on trial, charged with nine counts of indecent assault of a male dating back to the 1980s.

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He pleaded not guilty and his lawyer is arguing that the allegations are false.

Crown prosecutor Mark Hobart SC told the Downing Centre District Court that Magistrate Curran was 22 when he first met the boy, who was seven years old at the time.

Mr Hobart said the boy later regarded Magistrate Curran as part of the family and was babysat by him on occasions.

In 1980, when the boy was about 13, Magistrate Curran took the boy on a holiday to Europe, the court heard.

"[Family members] were very trusting of the accused, he was a very generous person, he bought them expensive gifts … the accused bought them a car and also paid off some of their debts," Mr Hobart said.

"They thought a lot of the accused and they trusted him … they themselves couldn't have afforded such a trip."

Mr Hobart said on this trip, the boy slept in the same room as Magistrate Curran, who would be naked.

When they returned, Magistrate Curran started taking the boy and his brother on Saturday sailing trips.

The court heard the pair would hold sleepovers at Magistrate Curran's Balmain home and the boy would be encouraged to sleep naked.

"The crown suggests that the accused, by doing this, was conditioning this boy or grooming him by asking him to sleep naked as if that was normal," he said.

'Ritual' during sleepovers

On Saturday mornings, it was alleged Magistrate Curran — then a solicitor — would engage in a "ritual" of pulling back the sheets and stroking the boy's naked body from head to toe while telling him to "just relax".

Mr Hobart told the court the complainant remembered Magistrate Curran would "become excited" during these rituals.

It was alleged on one occasion Magistrate Curran picked the boy up from a dance, where he had got a hickey from a girl he kissed there.

Mr Hobart said the accused slept in the same bed, noticed the bruise and became "extremely aroused" before fondling and kissing the complainant.

During the Easter holidays of 1981 or 1982 it was alleged Magistrate Curran pulled the boy's pants down and put his penis in his mouth on an overnight sailing trip.

The next day they sailed to a small bay where they allegedly swam naked and then went to a beach where the accused stroked the boy's penis.

On this trip, Magistrate Curran and the boy were tracked down in an air and sea search after they failed to call the boy's parents on the Friday night to say they were safe, the court heard.

Complainant 'mixed up', lawyer says

Magistrate Curran's lawyer Phillip Boulten SC said his client completely denied the allegations and will give evidence during the trial.

"Graeme Curran was a very close friend of the family and he became almost unconsciously a father figure," Mr Boulten said.

"He had a very affectionate relationship with [the parents] and all of their children, and he was a very generous and kind and caring part of the family."

Mr Boulten said Magistrate Curran had slept in the same bed as the boy on many occasions but they were always fully clothed.

He said the complainant had become very "mixed up" over the years and his allegations had become "bigger and better" over time.

"There was no ritual, as the crown prosecutor described it … the accused never got excited about a hickey on [the complainant's] neck, he never lost control of himself and kissed him," he said.

"[The complainant's] account of that [sailing] trip will be closely tested … he is quite wrong about many aspects of that trip … his version of what happened on that trip has developed significantly over time."