Volunteers would be expected to commit up to two hours of their time a week and would be given full training, supervision and support and out-of-pocket expenses.
The prosecutor said that he would see whether to pursue charges such as negligent supervision or injury to a child by omission, after the full results of the investigation were available.
Sir Roger said that despite safety assurances over Leeds General Infirmary, the full analysis of the data called for the children's heart surgery unit to remain under supervision.