The misconduct alleged by O'Brien included that police officers; O'Brien wished to have evidence admitted that would show that the two police officers leading the investigation against him had led two other cases where similar misconduct had been alleged; the Welsh bomb trial and the murder of Karen Price.

Contested trials last long enough as it is without spending time on evidence which is irrelevant and cannot affect the outcome.

"[5]Lord Bingham then concluded that evidence must satisfy a two-stage test before being admitted in a civil case.

The test of admissibility is that propounded by your Lordships' House in Director of Public Prosecutions v P [1991]2 AC 447.

The exercise of discretion as to whether admissible evidence should be permitted to be led involves the approach that the judge should bring to case management in accordance with the Civil Procedure Rules (CPR).