Cross-Examination of a Criminalist in a Gas Chromatograph Case (From Scientific and Expert Evidence - Second Edition, P 221-237, 1981, Edward J Imwinkelried, ed. - See NCJ-88831)

• NCJ Number: 88832
• Author(s): R A Hutton
• Date Published: 1981
• Length: 17 pages
• Sale Source: Practicing Law Institute
• Language: English
• Country: United States of America

Annotation

Effective cross-examination of a criminalist presenting blood alcohol evidence includes showing bias for the prosecution, lack of expertise, and the many possibilities for error in the use of the gas chromatograph to analyze the sample.

Abstract

Bias for the prosecution can be established by showing that the criminalist is employed by some branch of law enforcement, as is the case in almost every instance, and that the laboratory in which the criminalist works is used exclusively by police agencies. Lack of expertise may be established by indicating how often the criminalist testifies in court, leaving little time for scientific endeavors; lack of undergraduate or graduate courses in blood alcohol analysis and its relationship to sobriety; and lack of involvement in research that includes observing large numbers of people displaying various degrees of impairment under varying amounts of alcohol as measured by the gas chromatograph. A criminalist's own testimony may be used to cast doubt on the accuracy of the blood alcohol test by asking him/her to express an opinion about how much alcohol would have to be consumed to produce the results of the analysis. This may be shown to be greater than what the defendant actually consumed or that his/her behavior indicated. In exposing the possibility of error in the gas chromatograph analysis, the log book of the instrument should be summoned and reviewed to determine whether there is a disproportionate number of similar readings, which would suggest the instrument is malfunctioning. Maintenance records could also show how frequently the machine is repaired so as to indicate its vulnerability to error. The small sample measured should be highlighted and the assumption questioned that the small sample is representative of alcohol in the entire circulatory system. Further, the variations in sobriety between persons having the same amount of alcohol in the system should be emphasized. Forms used by the San Diego Police Department in processing blood alcohol tests are provided.