OTTAWA -- The Federal Court is ordering the RCMP to release the serial numbers of hundreds of its handguns in response to a request under the national information law.

In a decision made public Wednesday, Justice Nicholas McHaffie rejected the police force's argument the numbers amounted to personal information -- akin to a social insurance number -- that should be exempt from disclosure under the Access to Information Act.

In 2014, the RCMP received an access request for information related to a number of Sig Sauer P226 handguns.

In response, the Mounties released a 13-page chart that listed 468 P226 firearms along with details including the RCMP unit to which each gun had been issued.

The RCMP blacked out the serial numbers of the guns on the basis the numbers constituted information about identifiable individuals -- data considered exempt from release.

The requester, whose identity is protected, advised the Mounties the serial number of his own firearm had been redacted from the response. The RCMP did subsequently release the serial number of this gun, but maintained that the other numbers could not be disclosed.

The requester complained to the federal information commissioner, an ombudsman for users of the information law.

During the commissioner's investigation of the complaint, the RCMP pointed out that 85 per cent of the 468 serial numbers in the chart were linked to an individual in the Canadian Firearms Information System, with data including their name, date of birth and address.

The information commissioner sided with the requester and recommended release of the serial numbers, but the RCMP refused to budge, prompting the commissioner to take the matter to Federal Court.

During the court proceedings, the Mounties cited three other federal databases containing personal information to which the serial numbers could be linked. The RCMP also contended the numbers could be matched up with personal information held by private businesses, such as gun manufacturers or shooting clubs.

In his ruling, McHaffie said there was no serious possibility that release of the serial numbers to the requester would allow people associated with the relevant guns to be identified.

"To use the serial numbers to identify an individual would require either access to restricted government databases that already contain personal information, or a successful effort to trick either the government or the manufacturer into releasing personal information," he wrote.

"The evidence does not establish a serious possibility of either occurring."

McHaffie concluded the serial numbers were not personal information under the law. However, he noted the RCMP, believing otherwise, could have invoked a section of the access law permitting disclosure of the numbers in the public interest.

The judge found "no indication that the RCMP gave substantive consideration" to such a disclosure.

Exercise of the discretion demands a transparent and intelligible explanation of why the public interest in release does or does not clearly outweigh the relevant invasion of privacy. "The RCMP did not meet that standard."

This report by The Canadian Press was first published Nov. 6, 2019.