The Crown is not an ordinary adversary; its role is to see that justice is done. It therefore has a duty to disclose to the defence all relevant information in its possession, whether or not it helps the prosecution and whether or not it intends to call it as evidence.
The duty is triggered on request and is ongoing. It may be limited only where the material is clearly irrelevant or protected by a recognised privilege. A failure to disclose can breach the accused's right to make full answer and defence.
The Court held that the Crown has a legal duty to disclose all relevant material to the defence — whether or not it intends to rely on it, and subject only to limited privilege — because disclosure is essential to the right to make full answer and defence.