Halton police will review a host of recent cases in light of new statistics that show almost one in every three recent sex assault claims in the area are dismissed as baseless — but Hamilton police have not committed to any such review.

The revelations stem from a new Globe and Mail investigation that revealed police in Hamilton and Halton dismissed 30 per cent of sex assault claims over a five-year period as "unfounded," which is a number far higher than the national average of 19 per cent.

When an allegation is made to police and it is deemed unfounded, that means the investigator doesn't believe a criminal offence was attempted or occurred.

The way the two police services are handling the issue highlights some stark differences. Halton committed to an investigation right away, while Hamilton police have not directly addressed questions as to how they will respond to the numbers.

I expect that they will be looking at this and be commenting to the public, who have a right to know. - Lenore Lukasik-Foss , director of the Sexual Assault Centre of Hamilton

"The Police service is undertaking a review of all unfounded sexual assault occurrences, beginning with 2016, and will issue a media release when that review has been completed," said Halton police Sgt. Barry Malciw.

"We look forward to sharing the results of our reviews publicly in the very near future," Malciw said.

Police in London, Ont. (which also has a five-year unfounded rate of 30 per cent) have also committed to a similar review, stretching back to 2010.

By contrast, Hamilton police would not comment on the fact that two other police services with the exact same rate have committed to a review of their recent sex assault investigations.

"The Hamilton Police Service won't comment on the actions that are taking place with other agencies/police services," Const. Steve Welton said in an email.

When asked if the service has any specific plans to review the way it handles reported sexual assault complaints, Welton did not address that question directly. He instead pointed to mechanisms to increase reporting of offences, like telephone reporting, anonymous reporting and the finalization of an online system.

Welton said Hamilton police will speak further to the statistics and the context surrounding them in an interview on Tuesday.

Public has a right to know

Lenore Lukasik-Foss, the director of the Sexual Assault Centre of Hamilton, told CBC News that she expects some sort of review from local police, given the numbers and the response in other cities.

"I expect that they will be looking at this and be commenting to the public, who have a right to know," she said.

"I would understand if they said they needed some time to plan or work with community partners … but I would expect them to have a response."

Foss says the results of the Globe investigation mirror issues that are talked about often in her sector, and relayed to workers by survivors of sexual violence.

"For some they have a good experience, but there are others who just don't feel like they're being believed when they talk to the officer."

Assault cases less likely to be designated unfounded

Far fewer assault cases in the Hamilton area are listed as unfounded, compared to sexual assault. In 2014, just nine per cent of assault cases were deemed baseless, compared to 28 per cent of sexual assault cases.

But that's not the case in Halton. Investigators deemed 31 per cent of sex assault allegations in the region to unfounded in 2014, compared to 37 per cent of assault cases that year.

Some Ontario cities have far lower rates than Hamilton and Halton. Toronto police found just seven per cent of sexual assault allegations to be baseless, while Windsor is even lower at 3 per cent.

Niagara Regional police are just over the national average at 22 per cent.

Malciw told CBC News there are "a variety of reasons" that an incident reported to police can be cleared as unfounded.

"The reasons may vary from being as simple as an incident being improperly classified in the beginning to the investigation showing that the incident did not occur," he said, adding that the service views all sex assault allegations as "extremely important."

adam.carter@cbc.ca