Emma Farrar, a special needs pupil at Park school in Blackpool, drowned on November 13, 2001, during a weekly swimming lesson at nearby Woodlands school. The swimming instructor, Pauline Mills, 55, of Newton, near Kirkham in Lancashire, denied a charge of manslaughter.
Mr Justice Douglas Brown last week ordered a jury at Preston Crown Court to find Mrs Mills not guilty. She was also cleared of health and safety breaches along with Keith Berry, head of Park school. The case against them collapsed after the prosecution was unable to offer any further evidence.
Blackpool council had already pleaded guilty to exposing people not in its employment to health and safety risks. It was due to be sentenced yesterday.
Speaking outside court Nicholas Braslavsky QC, counsel for Mrs Mills, said:
"It has been very traumatic for Mrs Mills. She had devoted her life to swimming and I just think she wants to go home."
Her solicitor Jonathan Jackson said she felt that the most important aspect of the case was the tragic death of Emma Farrar and it was to her family that sympathy should be expressed.
He said it had been a distressing case for everyone in court.
The court's decision to acquit her showed Mrs Mills was not culpable in any way, Mr Jackson added.
He said 60 people had independently contacted his firm Clarkson Hirst before the case with personal testimonials supporting her.
Paul Schofield of Farleys solicitors, acting for Mr Berry, said the headteacher's deepest sympathies remained with Emma's family. He said: "The school community as a whole want to express their heartfelt condolences.
The last three years have been particularly difficult for everybody involved.
"Mr Berry has always maintained his innocence and this has now been vindicated by the outcome of the proceedings and in particular the manner in which they came to an end."
Emma's mother Samantha Ogden reacted angrily to the court's decision. She said: "How can a little girl go to school and die during a swimming lesson, and nobody is to blame?"