Ontario's privacy commissioner is investigating whether privacy rights were violated when police launched secret background checks on jurors.

Information and Privacy Commissioner Ann Cavoukian said the investigation is also necessary because the practice, in which police used confidential databases to probe the background of would-be jurors for Crown prosecutors, seems to be more widespread than the government had first indicated.

"Initially, the attorney general advised that this practice was restricted to one courthouse in Simcoe County," Cavoukian said in a release.

"Since then, we have learned that the practice extends to at least one other courthouse, and possibly others. As a result, we will be conducting our own investigation into this matter."

The president of the national Criminal Lawyers' Association on Wednesday also urged Ontario's attorney general to undertake a provincewide review of the problem.

"We know about these two regions because lawyers ferreted it out in those regions, but whether it takes place elsewhere is something he can tell us, and he hasn't yet," Frank Addario told CBC News.

"We need to have some transparency about how often and where it occurred and some guarantees it won't occur again. As for cases where it did occur, leave that to the courts to deal with."

Attorney General Chris Bentley said this week that while the problem is not widespread, the province's chief prosecutor has issued a directive to stop wide-ranging background checks.

Vetting is 'offensive'

The controversy began in Barrie when a judge declared a mistrial and two jury panels were dismissed last week. Then Tuesday in Windsor, a judge called the vetting process "offensive" and declared a mistrial in the first-degree murder case of Richard Zoldi and Shane Huard.

"In this case, the databank was used to weed out people who may not be favourably disposed to the police or to the Crown," Greg Goulin, one of the defence counsel in the Windsor trial, said in an interview Wednesday.

The information gleaned on potential jurors included their opinions of police based on, for example, their writing a letter to the editor criticizing police, any convictions they might have had as young offenders or any criminal pardons, among other things.

Records of people who were convicted as young offenders or those whose offences were pardoned are supposed to be sealed and aren't permitted to be shared in this way, Goulin said.

Moreover, "we have a Charter of Rights that says one has freedom of speech, freedom of expression and freedom of association," he added.

Some of the objections to potential jurors were based on their associations with convicted criminals, "which quite frankly simply could mean a family member who is in trouble and you're standing by them to try to rehabilitate them," Goulin said.

Background checks on jurors are supposed to only be conducted to find out about the most serious convictions. Under Canadian law, Crown or defence counsel are supposed to know only the name, address and occupation of prospective jurors.

Right to fair trial compromised

Having access to more background information compromises an accused person's right to a fair trial, Addario said.

"The Constitution promises a level playing field between the Crown and the defence, and here you have a situation where the state used its enormous financial resources to investigate jurors to gain an advantage in court. Obviously, only the wealthiest of the wealthy could afford investigators to do that," he said.

"Another problem is that the Constitution promises that when the Crown has information relevant to the proceedings [including jury selection], it has to disclose that to the defence — and again, that has to do with the state's enormous advantage over ordinary citizens in resources."

Even if the Crown had offered to share its background information with the defence, the checks on jurors were unacceptable, Goulin said.

"It's wrong to be done in the first place. A person is entitled to a jury of his peers, not a pristine jury, not a blue-ribbon jury."

The only two valid reasons potential jurors can be automatically ruled out are if they have been convicted of an indictable offence as an adult for which they have not been pardoned, or they have served more than 12 months in jail.

In light of the controversy, Goulin predicted a flood of defence challenges of cases currently before the courts and perhaps also retroactively.

At the least, he said, all defence lawyers from now on will demand to know whether jurors have been vetted and will seek to exclude police from courtrooms during jury selection.

With files from The Canadian Press