Nineteen Leicestershire Police officers were disciplined after a TV documentary secretly filmed them watching porn.
Chief Constable Matt Baggott apologised for their behaviour
The Independent Police Complaints Commission (IPCC) said five officers received formal written warnings and 14 others were "given advice".
The Channel 4 programme Undercover Copper was broadcast last year.
The IPCC criticised the ex-officer in the Dispatches programme, Nina Hobson, and Channel 4, for not co-operating with its investigation.
No action was taken against five other officers; one left the force for other reasons and one was unidentifiable, the IPCC added.
The programme also featured claims by Ms Hobson of derelictions of duty, including officers on patrol playing "hide-and-seek" in their cars and fetching takeaways while pretending to be busy.
An immediate investigation was ordered at the time by Leicestershire's Chief Constable, Matt Baggott, who apologised for the "poor behaviour" shown in the documentary.
The IPCC said: "Some of the unedited footage demonstrates that on many occasions when inappropriate behaviour was taking place, Nina Hobson was in fact the most senior officer on the shift and appeared to join in and encourage her colleagues."
It added that some of the footage transmitted appeared to have been shown out of context.
Channel 4 said: "Undercover Copper was an important investigation into an issue of major public interest. It prompted the IPCC to carry out an investigation which resulted in disciplinary procedures against 19 officers.
"We provided eight hours of untransmitted material to Leicestershire Constabulary to aid their investigation. This included the full, untransmitted footage surrounding every incident featured in the film.
"Viewers could see that the footage spoke for itself - all the footage was used fairly and accurately to represent the findings of the investigation.
"We are satisfied that Nina acted with the utmost integrity at all times. When witnessing bad practice by her colleagues she constantly questioned the appropriateness of their behaviour and whether it was standard practice.
"She was given clear instructions neither to instigate nor encourage bad behaviour."
In a statement issued through Channel 4's press office, Nina Hobson said: "At all times I put my role as a police officer first - I challenged every incident of bad practice and unacceptable behaviour I witnessed.
"My constant questioning of colleagues' actions and police culture is evident in footage used throughout the film."