An ex-candidate for Houghton Regis Town Council was fined after posting an image online of a police notebook containing details of investigations.
Roger Giugno, 50, pleaded guilty at Luton Magistrates Court on Monday to a charge of disclosing personal data, knowingly or recklessly, without the consent of the data controller.
On May 18 last year, a police officer left the notebook lying unattended in Mr Giugno’s presence after his arrest for another incident.
Mr Giugno photographed a page of the notebook and shared it on Facebook. Shortly afterwards, he posted a video in which he complained of his arrest, adding: “That ain’t the half of it, the silly copper in charge left her notebook behind.”
He told the court that he was continuing with a formal complaint against Beds Police.
Chairman of the bench, Martin White, said the disclosure could have been “devastating”.
He said: “This may not seem like a serious matter to yourself, but some of the data you disclosed actually had nothing to do with your case or grievance.
“There could have been details of police witnesses or informants, you don’t know what you were posting.”
The chairman added that it was “more luck rather than judgement” that no consequences arose from the leak.
Mr Giugno was ordered to pay a total of £315, made up of a £200 fine and other costs, along with destruction of the data.