"Mark Twain once said, 'Never let the truth get in the way of a good story'," barrister Steven Whybrow told the ACT Supreme Court on Tuesday.

"This case, you will hear, is the epitome of that phrase."

Mr Whybrow was addressing the allegation brought by former Liberal Party staffer Brittany Higgins, who has accused his client, Bruce Lehrmann, of sexually assaulting her at Parliament House.

Lehrmann, a former colleague of Ms Higgins, has gone on trial after pleading not guilty to a charge of engaging in sexual intercourse without consent.

Opening his case, ACT Director of Public Prosecutions Shane Drumgold SC said he would argue Lehrmann had committed the offence after "a drunken night out" with Ms Higgins and others.

Mr Drumgold outlined how the pair, working at the time for then-minister Linda Reynolds, were among a group of political staffers who initially went to The Dock in Kingston on a Friday night in March 2019.

Ms Higgins had about 10 drinks there before some of the group moved on to Civic nightclub 88mph.

She had at least one shot there and, according to Mr Drumgold, ended up feeling "as drunk as she had ever been in her life".

Mr Drumgold told jurors that when it came time for Ms Higgins to go home to Woden, where she lived at the time, Lehrmann suggested they share a car trip.

She recalled Lehrmann saying he needed to "pick something up from work" on the way home, and she did not argue against the idea because Parliament House "felt like a safe place".

The pair arrived at parliament about 1.41am on a Saturday morning, when Mr Drumgold said Lehrmann spoke with security staff.

"Oi, mate," Lehrmann was recorded telling security, according to Mr Drumgold.

"Bruce Lehrmann here with minister Reynolds. We've been requested to pick up some documents."

Mr Drumgold told jurors Lehrmann and Ms Higgins subsequently passed through a security check, where a guard noticed grass stains on the latter's dress.

Ms Higgins was too intoxicated to sign her own name, Mr Drumgold said, so Lehrmann did that for her.

The prosecutor said a guard then escorted the pair to the office of Senator Reynolds, who had just become defence industry minister, and left them there.

This, he told jurors, was where versions of events began to differ.

Mr Drumgold said Ms Higgins' evidence would be that she fell asleep on a couch in Senator Reynolds' office, and later woke to find Lehrmann raping her after feeling a pain in her thigh.

He told jurors Ms Higgins said no "half a dozen times" before Lehrmann stopped, looked at her and left.

"She was crying throughout the entire process," Mr Drumgold said.

Lehrmann was subsequently seen "hurrying through Parliament House" on his way to the exit, near which he threw a security pass onto a table as he left.

Mr Drumgold said he expected Lehrmann, who was later dismissed by Senator Reynolds for a security breach that morning and his previous "clumsy handling" of a classified document, would deny any sexual intercourse occurred.

But Mr Drumgold sought to cast doubt on the credibility of Lehrmann, who had given what were described as "various versions" of the morning in question.

The prosecutor said, for example, that the accused had denied telling security he had gone back to Parliament House after hours for official business, despite having been recorded giving that as the reason.

Mr Drumgold told jurors Lehrmann had also described returning to the building to pick up keys to his apartment and to drink whisky, both of which were "highly unlikely" to be true.

But in his opening address, Mr Whybrow said it was Ms Higgins whose version of events contained "massive inconsistencies and holes".

Mr Whybrow urged jurors to consider that Ms Higgins had not made a formal complaint to police until after the "massive media story" of her allegations had broken, turning the case into a "cause celebre".

Society had begun paying more attention to issues like sexual violence and workplace bullying, he said, meaning "this was a story whose time has come".

Mr Whybrow said the "bombshell" story of Ms Higgins' allegations had "rocked the entire political landscape", describing it as an "unstoppable snowball" that rolled down a mountain until it became an avalanche.

"The trial by media of Bruce Lehrmann was already under way," the defence barrister told jurors, adding that nothing - not even the "mundane" truth - was capable of stopping this "fantastic story" from dominating the news.

"The Australian public has been sold a pup with this story," Mr Whybrow told jurors.

"There has been a story out there which is not true."

The jury of 16, which has heard Senator Reynolds and other well-known political figures are among 52 names on the prosecution's witness list, began watching a video of a police interview late on Tuesday.

At the start of the February 2021 interview, Ms Higgins gave detectives her version of events and described having spent the weekend after the alleged rape "bunkered down, essentially in hysterics, crying".

The trial, which is expected to take between four and six weeks, continues.