The trial of a police officer accused of assaulting a G20 protester was hanging in the balance after the alleged victim failed to turn up to give evidence.
Metropolitan Police sergeant Delroy Smellie, 47, was due to go on trial charged with common assault by beating Nicola Fisher on April 2 last year.
But City of Westminster Magistrates' Court heard Ms Fisher was "unwilling" to attend court and prosecutors have been struggling to contact her.
Prosecutor Nick Paul said the case could go ahead using a witness statement she gave to the Independent Police Complaints Commission (IPCC) alongside video and photograph evidence.
But Smellie's solicitor Lisa Wilding said it would be unfair to use Ms Fisher's important evidence without being able to question her about it.
The court heard that Ms Fisher's former boyfriend Gavin Shepherd, who was due to be a witness, also failed to attend court.
The judge adjourned the case for prosecutors to make further inquiries about his whereabouts. The trial was due to be heard without a jury.
Mr Paul said Ms Fisher knows she is required in court as a witness summons was posted through her door after colleagues contacted her by telephone at the weekend.
The prosecutor said her former boyfriend, who witnessed the confrontation from a short distance, had "gone off the scene" and has only just been contacted.
The court heard that Ms Fisher claims to have been suffering from depression and has shown a doctor's note to an official from the IPCC at her home in Brighton. Ms Wilding said a doctor's note intended for work was "inadequate" and she would require disclosure of all medical notes about the witness's condition.