Privacy laws prohibit the sharing of information. We then need to look to the courts to get judicial authority, or some judicial body, not always the courts.
Interestingly we've had some situations recently where, if we don't believe that we have a criminal offence but we need information that's in a holding, which in fact will support it and stop the investigation, we can't apply for judicial authority to get access to information that would actually stop an investigation from continuing.