Because the assessment of cognitive function is among the most important diagnostic evaluations in medicolegal cases, neuropsychological testing, the optimal scientific method available to determine the manifestation of brain dysfunction, is a potentially very strong tool in those cases. However, the use of neuropsychological testing in a medicolegal setting should be done with caution.
 Firstly, the nature of any neuropsychological testing is complex, and cannot be simplified as“Test A measures Function A’”. Oversimplified explanation of a test is misleading, resulting in serious misjudgment in the legal procedure.
 Secondly, the result of the test shows someone’s cognitive function at the time of the test, not the time of the act in question（i. e., a crime）.
 Finally and most importantly, the cognitive function measured by neuropsychological testing does not directly correspond to the legal questions being asked, even when the terms used in the fields of law and neuroscience are similar. In determining whether an individual meets a specified legal standard（e. g., criminal responsibility）, the results of neuropsychological testing are far from sufficient and substantial additional information is required.
 With these caveats in mind, an expert witness should carefully choose the neuropsychological testing battery in each case, which may greatly help to understand the individual’s mental state at the time of the act in question.