Prosecutors have said that it would not be in the public interest to charge police whistleblowers who put former Chief Whip Andrew Mitchell’s ‘Plebgate’ altercation at Downing Street into the public domain.
However five police officers are facing gross misconduct hearings and another three are facing other disciplinary action.
PC Keith Wallis has been charged with misconduct in public office over claims that he sent an email to the deputy chief whip, John Randall, who was his MP, wrongly claiming that he had seen what happened in Downing Street last year.
The Sun reported on 20 September last year that Mitchell had been involved in a heated confrontation with a police officers after he was refused permission to cycle through the main gate of Downing Street. Mitchell later admitted swearing but denied the officer's claim that he had used the word pleb.
The following day the Daily Telegraph published a police log of the incident which backed up claims that Mitchell swore at officers and called them plebs.
The Sun is defending a libel action brought by Mitchell over its original Plebgate front page.
A spokesman said: "The CPS today concluded that it was in the public interest for the events at the gate of Downing Street to be made public. The Sun will be defending Mr Mitchell's libel action on the basis that our original story was true and published in the public interest."
The Independent Police Complaints Commission said that Wallis and four other colleagues will face gross misconduct proceedings over the row, meaning they could face the sack.
But prosecutors said there was no evidence of a criminal conspiracy against Mitchell, and no conclusive proof that either his account or the officer's account of what was said was correct.
The Crown Prosecution Service said that there was insufficient evidence to bring any charges against the officer at the gate, or a fellow constable who leaked an email giving his account of what happened.
Director of Public Prosecutions Alison Saunders said: "We have considered all of the evidence in this case, including previously unseen, unedited CCTV footage from Downing Street, not referred to by the media.
"Taking it all into account, including the accounts of the officer at the gate of Downing Street and that of Andrew Mitchell MP before, during and after the incident, we have found that there is insufficient evidence to show that the officer at the gate lied in his account. The CPS has also found that there is insufficient evidence to show that Mr Mitchell was the victim of a conspiracy of misinformation."
Lawyers found that a jury would be likely to decide that leaking the email was in the public interest.
Saunders said: "This type of conduct raises issues in relation to the right to freedom of expression, including the right to freely impart and receive information, and these are important rights enshrined in our law.
"In all the circumstances of this case, we have concluded that a jury is likely to decide that it was in the public interest for the events at the gate to be made public and it therefore follows that there is insufficient evidence to prosecute any suspect in relation to this leak."
She said previously unseen CCTV evidence and a string of emails and other messages between police and members of the public had been scrutinised as part of the investigation, and information relating to 14 people, 10 police officers, three members of the public and a journalist, was considered.
Eight people, including five police constables and three members of the public, were arrested in the wake of the affair and released on police bail until this week.
Saunders highlighted the conflicting accounts of what Mitchell said. The gate officer claims he used the words: "You should know your fucking place, you don't run this fucking government, you're fucking plebs."
However Mitchell claimed he said: "I thought you guys were supposed to fucking help us".
Saunders said: "We have been supplied with previously unseen and unedited footage of the incident from five different cameras. The CCTV footage does not determine the issue completely as it could be consistent with either the accounts of the officer on the gate or Mr Mitchell.
"It is clear from the footage that there was sufficient time for the words to have been said either as described by the gate officer or as described by Mr Mitchell, and this has been confirmed by an expert. The fact that an expert has confirmed what is possible does not of itself determine the issue.
"Our determination in relation to the incident also involved careful consideration of evidence concerning conduct and communications by officers and Mr Mitchell both before and after the incident, including the fact that Mr Mitchell's account has varied since the incident."
The CPS said there was "information but no admissible evidence" suggesting that an officer's partner contacted the media about the row, adding the word "morons" to the account, but a charge of misconduct in public office could not be brought because that person was a member of the public.
Another unconnected member of the public sent an email to the chairman of the Conservative Party claiming to have witnessed and filmed the incident, and alleging that the word "pleb" was not used, but again prosecutors could not bring a charge of misconduct in public office.
Charges of perverting the course of justice were also considered against two officers for statements they gave to the investigation, but there was insufficient evidence for a conviction.
A Channel 4 investigation appeared to cast doubt on the officers' account when it revealed CCTV footage which showed there was not a large group of tourists outside the main gate at the time as had originally been claimed.
The CPS said the programme "showed edited footage that was less than clear in a number of regards".
Scotland Yard said that, as well as the five officers facing gross misconduct charges, who would face a hearing over claims of discreditable conduct, honesty and integrity, and/or improper disclosure of information, another three would also face internal action.
Two would be subject to "local misconduct" proceedings for allegedly giving inaccurate statements or making inappropriate comments, while another has been recommended for management action for inappropriate comments.
Deborah Glass, from the IPCC, said "The Metropolitan Police has proposed, and I agree, that there is a case to answer for gross misconduct for that officer and four other officers from the Diplomatic Protection Group. We will take stock of the CPS decision made today and aim to publish further details in due course."
A statement from Channel 4 and ITN said: "The CCTV footage was obtained by Andrew Mitchell from Downing Street and provided to Dispatches and Channel 4 News.
"The footage as broadcast for the first time on December 18 2012 was not edited by the production team to change or alter the sequence of events.
"Furthermore, the three camera angles that we were provided with were image-matched frame by frame to confirm their veracity. We stand fully behind this investigation."
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