Often, it involves the production of a transcript of lip-read video-recordings of talk that lack a usable audiotrack, for example CCTV material.
[3] For many years, UK agencies made extensive use of one particular speechreader, whose reports are now not to be used for evidential purposes.
[5] Commissioning agents need to be aware of issues inherent in the unreliability of speechreading, and be prepared to treat such advice with caution.
It is the main reason why the accuracy of a speechreader working on a purely visual record cannot be considered wholly reliable, however skilled they may be and irrespective of hearing status.
In the US, there is debate concerning the admissibility of speechreading evidence and its status,[11] especially in relation to variations in state and federal evidential procedures, and with respect to the privacy implications of the Fourth Amendment to the US constitution.