Ms Higgins is being sued over a series of social media posts containing alleged mistruths the former defence minister believes have damaged her reputation.
Lawyer Martin Bennett told the court after Senator Reynolds finished her first day in the witness box Ms Higgins, who is in France, had posted on Instagram while her former boss was giving evidence.
"Ms Higgins thinks she can provide a social media running commentary on my client's evidence," he told the Western Australian Supreme Court on Monday.
"It's extraordinarily inappropriate."
Linda Reynolds' lawyer has accused Brittany Higgins of commentating on the trial. (Richard Wainwright/AAP PHOTOS)
The post is a photo of a book titled How Many More Women? How the law silences women, along with the words: "Pertinent reading".
Mr Bennett said the senator would submit an amended statement of claim on Tuesday to reflect the post.
"I would hope somebody would advise Ms Higgins to give up commentary," he said.
Ms Higgins' lawyer Rachael Young said it was a repost and had no bearing on the trial.
Outside court, Mr Bennett said the post could aggravate any damages awarded to the senator.
Earlier, Senator Reynolds told the court she was angry when she learned about a "major security breach" at her ministerial office involving Bruce Lehrmann and Ms Higgins, who were intoxicated.
"I was a bit gobsmacked, I was then angry ... the stupidity of the staff to do that," she said.
The senator said she was initially embarrassed for Ms Higgins when she learned security staff found her naked.
The then-24-year-old later reported having very little memory of the events in the office.
"I felt a bit sorry for her because it would have been a bit embarrassing to have woken up the next morning after having been asleep drunk in your boss's office," she said.
In the days following Senator Reynolds met Ms Higgins in the same office she was allegedly raped in, which has since been used to illustrate her alleged mishandling of the rape.
"There was no allegation of rape and there was no indication of where, when she said that 'he was on top of me' that it was actually in my office," she said.Â
"So when we had the meeting, it seemed the logical place to do it, because it was the only private room that I had a meeting like that in."
Lawyer Rachael Young (centre) defended the social media post by Brittany Higgins. (Richard Wainwright/AAP PHOTOS)
Senator Reynolds said she was impressed with Ms Higgins at the meeting.
"She was sorry, she took responsibility for her actions and she wanted to stay working for me," she said referring to the security breach.
The senator assured Ms Higgins, who was upset and embarrassed by the incident, her job was safe and offered to help her make a complaint to police about Mr Lehrmann.
"She did not say that there'd been any sexual assault, she did not say there'd been a crime but (then-chief of staff Fiona Brown) and I were both worried," she said.
Lehrmann denies sexually assaulting Ms Higgins. His criminal trial was aborted because of juror misconduct and Ms Higgins' mental health was cited as the reason for no retrial.
The senator will resume giving evidence on Tuesday.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
8°C