Everyday knowledge about language and speech, or ‘folk linguistics’, incorporates a number of false beliefs that have a negative effect in a range of areas, nowhere more so than in the criminal justice system. One lesser known area where false beliefs have a major impact is forensic transcription (interpretation of indistinct covert recordings used as evidence in criminal trials). Without consultation of the linguistic sciences, the law has developed processes that allow police transcripts to ‘assist’ the courts in making out unintelligible covert recordings. The present article uses a case study of a real murder trial to bring the actual and potential injustice this creates to the attention of linguistic science, and examine the issues from a linguistics perspective. Having laid out the problem, it goes on to consider potential solutions, arguing that creating a better process requires deep collaboration between linguistics, law and law enforcement. From linguists, it requires improved theoretical understanding of the nature and structure of the false beliefs that underlie the existing legal processes, as well as development of a more general theoretical account of the process of transcription and the nature of transcripts.