SUDBURY -- A judge in Sudbury ruled Monday that four of five search warrants issued during the investigation of Sudbury doctor Ian MacDonald are invalid because they were improperly filled out.

MacDonald is charged with seven counts of accessing child pornography between 2016 and 2019. Ontario Court Justice Heather Mendes ruled the error on the warrants could not be altered to make them compliant with the law, as Crown Attorney Stephanie Baker argued.

Instead, she accepted arguments from defence lawyer Michael Lacy, who said accepting the Crown's request would be the equivalent of rewriting the warrants after the fact.

The warrants include searches of MacDonald's two vehicles, his home and a building on his property. Those search warrants were executed in May 2019.

An earlier warrant issued in April for MacDonald's hospital computer at Health Sciences is still valid.

In a July hearing, Lacy argued the warrants were faulty because they were issued with the wrong box checked. Instead of saying police were searching for evidence related to a crime, the box checked said a "suspected" crime.

That's significant because previous judgments have said warrants for suspected offences can only be issued for where the offence is suspected to have taken place – in this case, the hospital. Broader warrants can only be issued once police know an offence has been committed.

Mendes said rewriting the warrants now to fix "sloppy work" or the ignorance of the officer who filled them out is going much farther than previous decisions, which have allowed more minor alterations.

"It's vitally important that warrants are clear on their face," Mendes said. "I decline to sever the word suspected ... as this would be altering the warrants."

Mendes also ruled a Sudbury police officer with the Internet Child Exploitation unit will have to testify. The officer asked MacDonald for the password to his computer – a practice that is not allowed. It turns out that was the officer's normal practice, and now 13 other child pornography cases are under review as a result.

Lacy also wants to question the officer about whether there was full disclosure in his narrative about how the investigation unfolded.

"We need to decide how we are going to proceed," Baker told Mendes, in asking for some time to reassess the Crown's approach in light of Monday's ruling.

The parties will be back in court Oct. 7, with an eye on setting trial dates for December.