An Ontario judge will decide whether to make the details public of why police arrested and charged former nurse Elizabeth Wettlaufer with multiple counts of first degree and attempted murder.

Postmedia is fighting to lift a ban on search warrant information including a summary of an interview with the former nurse's psychatrist that may describe her alleged confession, as well as interviews with former nursing home employers and a friend of Wettlaufer. 

Arguing in a Woodstock courtroom on Monday, lawyer Brendan Hughes said the public has the right to scrutinize the way police carried out the early stages of the investigation, and that redacting the documents is not justified. 

"I submit that the documents should be unsealed unless you find the redactions predjudicial," Hughes told Ontario superior court judge Thomas Heeney.

Heeney must weigh whether information blacked out on dozens of pages could compromise Wettlaufer's right to a fair trial, if it contains evidence that could incriminate her.

Redacted copies of Wettlaufer warrants

Details of why police arrested and charged Elizabeth Wettlaufer, contained in search warrants, have been redacted. (Amanda Margison/CBC)

The 49-year old is accused of using insulin injections to kill 8 seniors and harm 6 others in her care at three Southwestern Ontario nursing homes and a private residence between 2007 and 2016. 

Wettlaufer's defence lawyer Brad Burgess and Crown attorney Peter Scrutton stood on the same side of the courtroom to defend the publication ban. 

"The information that is redacted is very obviously incriminating. We think there is a risk to a fair trial," Scrutton said. 

He worries potential jurors will be biased if they read the sealed material and noted that even if the trial were held outside of Southwestern Ontario, media coverage of the Wettlaufer case is national and available to everyone on the internet.  

Over 20 pages of documents are blacked out

Unredacted portions of the search warrant show Wettlaufer was under the care of a psychiatrist at Toronto's Centre for Addiction and Mental Health on September 16, 2016, one month after allegedly attempting to kill final victim 68-year-old Beverly Bertram. 

A summary of a police interview with her treating psychiatrist spans 20 pages and all of it blacked out. 

Other redacted information includes Wettlaufer's employment record, patients under her care, and interviews conducted by police, including one with a friend of the accused. 

Hughes cited other high profile cases where search warrant seals were lifted, sometimes partially, in the interest of press freedom and the public's right to know including Toronto's Project Traveller drug raids that revealed the late Rob Ford smoking crack cocaine. 

Judge Heeney pressed Postmedia lawyer Hughes on the fact the media coverage around Wettlaufer's case is "extraordinary."

"At times it is," Hughes agreed, "but it's not the level of media interest that matters here. It's whether the ban is justified under the law." 

Heeney did not say when he would have a decision but before adjournment, he told the court writing a decision would be challenging.