An ACT Supreme Court jury of eight women and four men retired about 3pm on Wednesday to consider its decision in the trial of former Liberal Party staffer Bruce Lehrmann.

Lehrmann, 27, denies raping former colleague Brittany Higgins in the ministerial office of their boss at the time, Senator Linda Reynolds, after "a drunken night out" in March 2019.

He has pleaded not guilty to a charge of engaging in sexual intercourse without consent, insisting no sexual activity took place when the pair attended Parliament House in the early hours of a Saturday morning.

When the court reconvened at 4pm on Thursday, Chief Justice Lucy McCallum said she had not heard from jurors throughout the day and assumed they would want to go home.

Some members of the jury nodded in response, and the judge asked them to come back at 10am on Friday to continue deliberating.

"I remind you that I'm here to help you," Chief Justice McCallum told the jury.

A jury of 16 was empanelled when the trial began on October 4, with the court choosing a larger than usual number in case some needed to be discharged during the course of a trial that initially had an estimated duration of between four and six weeks.

However, it only took a little more than two weeks to complete the evidence of 29 witnesses, including Ms Higgins, and addresses from the prosecution and defence.

All 16 jurors stayed the course, meaning four had to be "voted off the island", as Chief Justice McCallum put it, before the final 12 commenced deliberations on Wednesday.

The judge has told jurors "the principal issue" they must determine is whether sexual intercourse occurred at all on the morning in question.

Prosecutor Shane Drumgold SC's case is that Lehrmann raped Ms Higgins on a couch in Senator Reynolds' office after she had drunkenly fallen asleep or passed out there.

Mr Drumgold closed his case by telling the jury Ms Higgins was "an inherently credible witness", who was "right to be scared" of reporting the alleged rape because of political ramifications.

Defence barrister Steven Whybrow argues Lehrmann never entered the room in which security guard Nikola Anderson claims to have found a naked Ms Higgins on the couch.

Mr Whybrow, who says Ms Higgins "doesn't know what happened", has suggested she fabricated the rape allegation because she was worried about being sacked after the early morning entry to the senator's office was declared "a security breach".

MORE COVERAGE OF THE TRIAL: