A trial is due to start in May, and the two-day hearing this week is to decide what evidence can be used when that comes around.
The "Wagatha Christie" row broke out in 2019 when Mrs Rooney said fake stories were leaked to the press after only being seen by Mrs Vardy's Instagram.
Mrs Vardy denies the accusations and is suing Mrs Rooney for libel.
On Tuesday, the High Court heard that WhatsApp messages between Mrs Vardy and her PR and friend Caroline Watt had been disclosed ahead of the trial.
And it's what's in those messages that has been discussed in court today.
On the day Mrs Rooney, the wife of former England star Wayne, published a post on Twitter which ended, "It's.......... Rebekah Vardy's account", Mrs Vardy sent a message to Ms Watt, stating: "That's war."
The messages also revealed Mrs Vardy referred to Mrs Rooney and her husband Wayne with offensive language.
One non-expletive term called Mrs Rooney "nasty".
Mrs Rooney's lawyers have previously claimed that Mrs Vardy, who is married to Leicester City striker Jamie, had leaked information to The Sun newspaper either directly or through Ms Watt "acting on her instruction or with her knowing approval".
In written arguments, Mrs Rooney's barrister David Sherborne said: "From the outset, Mrs Vardy has always claimed that neither she nor Ms Watt were involved in the leaking of private information from Mrs Rooney's Instagram account.
"The recent disclosure has shown that this is emphatically not the case," he added - referring to those WhatsApp messages.
According to Mrs Rooney's written case, messages between Mrs Vardy and Ms Watt in January 2019 showed them discussing a post on Mrs Rooney's private Instagram where her car had been damaged.
Mrs Vardy told Ms Watt she "would love to leak those stories x".
Mr Sherborne said Ms Watt was later responsible for the leak of the story to the newspaper, with Mrs Vardy's approval.
After the story was published in The Sun Mrs Rooney tweeted it was "sad" someone who followed her was "betraying" her.
According to written submissions, while discussing the tweet in a private WhatsApp conversation, Ms Watt told Mrs Vardy "It wasn't someone she trusted. It was me", in a message accompanied by a laughing emoji.
In written arguments Mrs Rooney's barrister said this "conspicuously elicits neither surprise, contradiction or criticism from Mrs Vardy, who was plainly aware and approved of this leak".
At the hearing on Tuesday, which is due to last two days, Mr Sherborne said Mrs Rooney had brought a claim against Ms Watt for misuse of private information, which Ms Watt denies.
He added that Mrs Rooney's legal team had wanted more information from the WhatsApp messages between Mrs Vardy and Ms Watt, but said Ms Watt's phone had "regrettably" fallen into the North Sea after a boat she was on hit a wave, shortly after the last court hearing.
"[It was] most unfortunate, because it was only a short time after the court ordered that the phone should be specifically searched," he said.
Hugh Tomlinson QC, representing Mrs Vardy, said the denied allegations have caused her "huge damage and distress".
In written arguments, the barrister said the information and messages disclosed "provides no evidence that the claimant leaked the three fake posts".
He said Mrs Rooney "relies upon selective and incomplete WhatsApp exchanges... conveniently ignoring the messages which demonstrate beyond doubt that the claimant was not responsible for leaking the defendant's private information to The Sun".
In further WhatsApp messages between her and Ms Watt, Mrs Vardy said she had supported Mrs Rooney and suggested it was Mrs Rooney's own PR who had leaked stories.
Ian Helme, for Ms Watt, said she had given "clear and consistent" denials against the claim for misuse of private information.
The barrister said in written arguments that it was not only Mrs Vardy's Instagram account that had viewed the post about Mrs Rooney's car, adding that the incident also took place in public.
"It is difficult to see how there could be said to be any reasonable expectation of privacy in relation to such information," Mr Helme said.
He later said that Mrs Rooney's lawyers had taken "an extremely aggressive" approach and added it can be inferred that Mrs Rooney's primary concern is "public opinion, or vindication".
The trial is due to start in early May.
The hearing before Mrs Justice Steyn is due to finish on Wednesday.