Lawyers for Liberal senator Linda Reynolds are poring over tens of thousands of pages of potential evidence taken from Brittany Higgins' phone.
The former defence minister, who plans to retire from politics at the next election, is suing her former political staffer over a series of social media posts she says damaged her reputation.
Mediation has failed to resolve the case, which returned to the WA Supreme Court on Monday for a directions hearing ahead of an August trial.
Senator Reynolds' lawyer Martin Bennett said his team was working through documents Network Ten supplied on subpoena, including a report on Ms Higgins' mobile phone.
The documents are from Bruce Lehrmann's failed defamation case against the media outlet and Lisa Wilkinson.
"The Australian Federal Police download of Ms Higgins' telephone, which is 56,287 pages," he told reporters outside the court.
"So we're working through that and marrying that up against discovery."
Some of the pages could become evidence in the high-profile defamation battle, scheduled to start on August 2.
"Already we can see documents within it that are useful ... It's a haystack," he said.
Mr Bennett said the documents, along with Senator Reynolds' recent trip to Washington with a parliamentary delegation to the NATO summit, had slowed preparations but would not delay the trial.
Ms Higgins has meanwhile revealed she is pregnant.
"Beyond excited to welcome a new member to our little family," she wrote on Instagram on Sunday.
"Your parents are already obsessed with you and you aren't even here yet."
The baby news hadn't triggered talks about a fresh attempt at mediation to resolve the matter before the trial, Mr Bennett said.
The court battle is expected to hear from about 20 witnesses over four to five weeks.
Former prime minister Scott Morrison could be among them, along with other members of the federal Liberal Party including senators Michaelia Cash and Wendy Askew.
