Sixty-seven officers or staff have been investigated for police computer misuse in Northern Ireland over the last three years, records show.
Suspected data protection breaches involved inappropriate access to PSNI systems.
The alleged wrongdoing, also covering social media, involved a tiny minority of nearly 10,000 employees.
One officer was cautioned recently after he opened files relating to an allegation of assault made against him by a member of the public.
Daniel Nesbitt, a campaigner and director of Big Brother Watch, said: "In a time where we are all now digital citizens, more of our information is going to be held than ever before and the police have to be up to the task of keeping it safe.
"It's high time that the most serious data breaches are punished with custodial sentences and criminal records."
Police computers hold records of interactions with people as well as sensitive material relating to operations.
Fifteen officers were investigated for misuse of computers in 2015/16, with 30 cases over the previous two years, details disclosed by the PSNI revealed.
A total of 22 police staff were investigated over the same period.
In a case pursued recently by the Police Ombudsman, a routine audit showed an officer had accessed records from the investigation into a colleague's conduct.
Ombudsman investigators asked police to check whether the officer had also accessed records about a probe into his own conduct. Another audit showed that he had.
The officer accepted he had no lawful reason for opening any of the records.
A report by Her Majesty's Inspectorate of Constabulary on the integrity of crime data said the PSNI performed strongly compared with counterparts in England and Wales.
A PSNI statement said: "Whilst PSNI officers are expected to behave with the highest standards of professionalism and integrity at all times, the number of officers outlined in this response should be should be placed in context with the average strength of the PSNI in the time-frame requested, which is around 7,000 regular officers and 400 part-time police officers."
The statement added that the average number of police staff in the time-frame was around 2,400.
Mr Nesbitt said any data breach had the potential to be serious and citizens should be able to trust that their personal information will be protected.