Slade & Ors, R. v

Where the prosecution makes a factual allegation a central plank of its case, the safety of the resulting conviction must be assessed on that case. An appellate court may consider a compelling analysis founded on material available at trial where justice requires it and the analysis demonstrates that the factual premise was wrong.

The one-trial principle remains important when deciding whether to receive fresh expert evidence under section 23 of the Criminal Appeal Act 1968. The court must balance it against the need to avoid a wrongful conviction. Automatic speaker-recognition evidence based on likelihood ratios was not admitted where its statistical basis, operation and presentation to a jury had not been satisfactorily established.

Following jury trials at Leeds Crown Court, Slade, Pearman and Baxter were convicted on the first indictment of conspiracy to murder Ralph Roberts and related offences. The prosecution relied on covert recordings from a stolen Audi RS6 and alleged that the appellants were the speakers discussing the intended killing.

The appeals concerned the first-indictment convictions. The appellants challenged the refusal of their submission of no case to answer, the summing-up, a jury incident and late disclosure. They also relied on detailed analysis of CCTV, telephone, cell-site and tracking material, and sought to adduce expert CCTV and automatic speaker-recognition evidence. The central issue was whether the convictions were safe after the prosecution's asserted identification of the RS6 speakers had been undermined.

1. The appeals against conviction were allowed and all convictions on the first indictment were quashed. The Crown had advanced the appellants’ presence in the RS6, and their participation in the recorded conversations, as a central and crucial plank of its case. The safety of the convictions had to be assessed on that case, not on an alternative theory which the Crown had not advanced at trial.

2. The trial judge had been entitled, on the evidence and arguments then presented, to reject the submission of no case to answer under the Galbraith approach. A judge need not search the entire evidence for further arguments not advanced by the defence. That ruling was not disturbed on its own terms.

3. However, in the interests of justice, the court considered the appellants’ fuller CCTV, mobile-phone, cell-site and tracking analysis. It demonstrated that the CCTV clock at Slade’s home was consistently about 22 minutes slow throughout the relevant period. The inference that Baxter, and on occasions Slade, were in the RS6 was thereby unavailable. The telephone and text evidence, and other material, reinforced that conclusion.

4. The jury had been directed that it could reject the appellants’ alibi arguments and find that they were the RS6 speakers. Once that central factual basis was removed, the convictions were unsafe. The same conclusion applied to the handling count because it covered the same indictment period. The Crown did not seek differing outcomes between the three appellants.

5. The court refused to admit the proposed CCTV expert evidence. It could reasonably have been obtained and deployed at trial, and the point was in any event established by the accepted schedules. It also refused the automatic speaker-recognition evidence. The small reference population, error rate, unexplained software choices, potential variation between systems and difficulty of fair jury evaluation meant that its likelihood-ratio conclusions had not been sufficiently justified. The court made no definitive ruling on future admissibility of such evidence.

• Court of Appeal (Criminal Division): appeals against the first-indictment convictions allowed and the convictions quashed: [2015] EWCA Crim 71.

• Crown Court at Leeds: before HHJ Hoffman and a jury, Slade, Pearman and Baxter were convicted on 20 August 2009 of conspiracy to murder and related offences. Applications by Pearman and Baxter to appeal against convictions on the separate second indictment had previously been rejected by the Court of Appeal, but no citation is stated in the judgment.