Welding fume litigation requires testimony to complex scientific issues concurrent with findings from specific medical maladies in neurology, toxicology and epidemiology. Physical science, engineering assessments and medical diagnosis are expected to converge and form a legal consensus which does not always happen. The testimony of experts must be complementary from engineers and the medical community for each case, date, process and workplace. Accurate data about resultant personnel disorders and biological dysfunctions are often not easily exchanged between engineers and medical practitioners. Reports of findings can be biased, misleading and violate common sense.