Mold exposure in damp buildings has become an increasing subject of litigation over the last decade. Often times, these claims are supported by a medical analysis called differential diagnosis. This method as been used by physicians to attribute various symptoms to inhalation of mold in water-damaged buildings. Rather than demonstrating a specific exposure to a specific mold resulting in a specific reaction, differential diagnosis uses a process that “rules out” or “rules in” possible causes of symptoms a patient is experiencing to determine that their symptoms are related to exposure to mold. Differential diagnosis has been frequently used to show an association between exposure to mold in wet buildings and certain human health effects. In its opinion in the case of Montgomery Mutual Insurance Co. v. Chesson, the Maryland Court of Special Appeals held that this method is not sufficiently accepted in the scientific community so as to be used as a basis for medical testimony in mold cases. The Court of Special Appeals reversed a trial court ruling that found such medical testimony to be reliable and admissible.