On manual laterality (handedness) in humans and its forensic significance - a literature review.

Manual laterality (handedness) in humans has some significance for forensic practice where it is primarily employed in the form of handedness preference, based on a simplified three-stage classification (right-handed, left-handed and ambidextrous). In cases of homicide or suicide, the pattern of injuries, particularly cutting or stab injuries and gunshot wounds, may provide clues as to the perpetrator's handedness. In injuries inflicted by another person, the pattern of findings can in isolated cases allow to draw conclusions as to the handedness of the perpetrator. In self-inflicted injuries and suicide, the dominant hand is usually used either alone or as the lead hand. If it is found that fatal injuries were inflicted by the non-dominant hand, this gives rise to doubt that the manner of death is suicide. Evidence of handedness is of little value in distinguishing between suicide and homicide. Due to new developments in dentistry, imaging procedures and especially genetics, the utility of handedness in the identification of unknown persons or cadavers has significantly diminished. In living subjects, useful evidence of handedness can be obtained by observing the performance of specific gestures or activities. The subject should be asked to perform tasks involving one and two hands in a specific sequence. Standardised measurements of the morphology of the shoulders and upper extremities are able to make a statistical distinction between right and left. Since the accuracy of this process is, however, only,around 75 %, morphological determination of handedness should not be used in living subjects, but should be restricted to the identification of unknown cadavers or other post-mortem examinations.