A trial at Preston Crown Court was abandoned after a police officer sat in court started making facial expressions while a defendant was giving evidence.
A judge discharged the jury on Tuesday during the trial of a 22-year-old man who was accused of aggravated burglary at a home in Chorley, Lancashire.
Members of the jury became concerned about “facial expressions” being made by the officer during the evidence and brought it to the court’s attention.
The defendant’s legal team applied to Judge Graham Knowles QC to have the proceedings halted.
The judge stopped the case and discharged the jury on the grounds of the conduct and behaviour of the police officer.
The case had taken six months to get to trial and cost more than £1,600 in Crown Prosecution Service costs alone.
It will now be September 17 before a new trial is held.
A spokesman for the Judicial Office, which runs courts in England and Wales, said: “Questions were raised by the jury about facial expressions made during the defendant’s evidence by someone who was subsequently identified as a police officer.
“The defence applied to the trial judge for the jury to be discharged. After hearing from the defence and the prosecution Judge Knowles QC discharged the jury. A new trial will take place in September.”
A spokesman for the Crown Prosecution Service said: “As a result of a matter brought to the attention of the judge during the trial, a decision was made to discharge the jury. There will be a retrial on September 17.”
The cop has denied pulling faces in court.