Why "Ad Hoc Experts" Should Not Provide Transcripts of Indistinct Forensic Audio, and a Proposal for a Better Approach

Indistinct covert audio recordings frequently figure in criminal trials together with transcripts prepared by police officers who have been accorded the status of ad hoc experts on the basis of their prolonged and repeated exposure to the recordings. Drawing on research in linguistic and phonetic science, we explain why such transcripts are highly prone to be unreliable, why they may mislead juries into misinterpreting the contents of the conversations and why current court procedures for mitigating this risk are inadequate. We conclude by outlining a proposal drawn up and endorsed by senior expert linguists for establishing a process whereby reliable transcripts of indistinct covert recordings can be provided for juries.