One police officer is to be charged with misconduct in a public office as a result of the "Plebgate" row involving Andrew Mitchell and police.
But the Crown Prosecution Service said there was insufficient evidence to show that the officer at Downing Street's gate lied in his account.
Mr Mitchell was accused of calling officers "plebs" after they stopped him cycling through the gates.
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."
But the CPS said it had decided to charge PC Keith Wallis with misconduct in a public office over the allegation he falsely claimed to have witnessed the incident in an email to deputy chief whip, John Randall who was his MP.
PC Wallis has been charged and is required to attend Westminster Magistrates' Court on 16 December 2013.