People's privacy may have been breached in the ACT by police, after a damning investigation found ACT Policing may have illegally accessed telecommunications data.
An Ombudsman report found that the territory's police only complied with the proper procedures to access location-based services data, known as pings, nine out of more than 1700 times over a four-year period from 2015 to 2019.
But compliance issues in accessing the data go back to 2007, the report says.
In some of these cases, the data may have been used by the prosecution in a court.
The report shows several examples where police officers had accessed pings prior to receiving formal approval.
In one case, a police officer had accessed the data without approval as their reporting officer was "in a meeting". The officer then said they would submit an approval request "at some point".
The accesses to pings were not compliant with the Telecommunications (Interception and Access) Act, Commonwealth Ombudsman Michael Manthorpe said.
He said many of the authorisations for pings were not properly authorised or reported to the Ombudsman or relevant Commonwealth minister.
"My office's investigation identified that the internal procedures at ACT Policing and cavalier approach to exercising telecommunications data powers resulted in a culture that did not promote compliance with the TIA Act," Mr Manthorpe said.
"This contributed to the non-compliance identified in this report."
Mr Manthorpe said this meant many pings may have been accessed unlawfully and that people's privacy may have been breached.
"This could have a number of potential consequences, for example, the privacy of individuals may have been breached and we have been unable to rule out the possibility that unauthorised [pings] may have been used for prosecutorial purposes," he said.
The Ombudsman also said both the Australian Federal Police and ACT Policing missed a number of opportunities to identify the unlawful breaches.
"Law enforcement agencies rely on a wide range of covert and intrusive tools to do their work, but to maintain public trust these tools need to be properly deployed, in accordance with the legislation which governs their use," Mr Manthorpe said.
ACT Policing were able to view the report before it was made public.

ACT Chief Police Officer Neil Gaughan said police had implemented a number of measures to prevent issues from reoccurring.
"As police officers we have access to special powers for investigative purposes to ensure the safety of the entire community. We take this responsibility seriously, and accept and apologise for our past non-compliance outlined in the Ombudsman's report," he said.
"I want the community to be assured that we have changed our approach to requesting and approving access to mobile device locations, which my officers are implementing daily."
More to come.