People v. Tobey

In 1973, a jury convicted Bradley Tobey (defendant) of two counts of illegal sale of heroin. The prosecution’s (plaintiff) trial evidence against Tobey included three expert witnesses who testified about voiceprint identification testing over Tobey’s timely objections. The experts explained that voiceprint operators could compare two voice recordings to determine whether the same person spoke in each recording. Voiceprint operators used a tool called a spectrograph to generate patterns called spectrograms to make their comparisons. On February 28, 1972, a police officer recorded two phone conversations with a person believed to be Tobey. On December 6, 1972, the trial court compelled Tobey to provide voice exemplars by speaking the same words from the recorded phone conversations into a recording device. At trial, two of the voiceprint experts opined that Tobey’s exemplars matched the voice in the recorded phone conversations. One of the expert witnesses testified that nothing was done to the spectrograph to account for any difference between the telephone recording and Tobey’s exemplar, which was not produced through a telephone, although another witness testified that voiceprint comparison should consider that variable. The expert witnesses also admitted that the spectrograph was never maintained or calibrated; the police’s spectrograph was generally not checked unless it stopped generating a spectrogram pattern. One expert witness testified that no experiment had ever verified the use of samples recorded more than one month apart, but research revealed that there were more errors in voiceprint comparisons in which samples were recorded one month apart than in comparisons in which samples were recorded at the same time. Tobey appealed, contesting that the trial court had erred by allowing the prosecution to present expert witnesses without first laying a proper foundation for the admission of the witnesses’ testimony.