594 example, the explosive proliferation of print and broadcast media, as well as internet attention, to “toxic mold” has contributed to the public’s attention to and fear of even minute and harmless amounts of indoor contaminants. Physicians, too, have, at times, contributed to patients’ beliefs that they are ill and that certain environmental factors are the cause. By misattributing symptoms to a cause or diagnosis of questionable validity, a physician can encour- age and reinforce a patient’s notions and exacerbate the illness through an iatrogenic effect [27]. All these issues, reporting bias, hazard perception, and iatrogenic contribu- tion, have been studied and documented [28–36]. Patient and physician biases contribute both to the diagnostic inter- action between the clinician and the patient/claimant, as well as to the causal attribution and analysis by the clinician. Legal Causation Analysis The determination of legal causation of a medical illness requires expert medical testimony on the medical and environ- mental cause of injuries. This commonly includes a detailed toxicological, epidemiological, and/or, at times, an industrial hygiene-supported causal assessment. Whether or not the med- ical opinion is admissible depends on whether it meets court- accepted standards of reliability. In many states, and in federal courts, that standard is known as the “Daubert standard.” Admissibility of Expert Testimony The specific legal rule in federal court pertaining to whether an expert’s testimony is admissible is found in Rule 702 of the Federal Rules of Evidence. The rule also applies to other experts as well as to physicians. A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if: 1. The expert’s scientific, technical, or other specialized knowledge will help the trier of fact (a judge or jury) to understand the evidence or to determine a fact in issue; 2. The testimony is based on sufficient facts or data; 3. The testimony is the product of reliable principles and methods; and 4. The expert has reliably applied the principles and meth- ods to the facts of the case. Daubert Criteria In 1993, the U.S. Supreme Court clarified Rule 702 and the admissibility of expert medical testimony in a case known as Curr Allergy Asthma Rep (2012) 12:590–598 Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).The Daubert case set out four factors used by the courts in determining whether an expert witnesses’ the- ory, technique, or opinion on the causing of a medical illness is scientifically or medically valid such as to allow it to be considered in the case. This standard is now used by courts to determine whether a physician’s opinion on medical causation is admissible in evidence for consideration by the court or the jury. The Daubert factors and Rule 702 provide the standard for determining legal causation in a civil lawsuit. Those four primary, but non-exclusive, Daubert factors are: 1. Can or has the medical or scientific theory, knowledge, opinion, or technique been tested? 2. Has the medical or scientific theory, knowledge, opin- ion, or technique been subjected to publication and peer review? 3. Is there a known or potential rate of error for the meth- od, knowledge, opinion, or technique? 4. Is the medical or scientific theory, knowledge, opinion, or technique accepted by the majority of other medical or scientific peers within the relevant medical or scien- tific community? These four Daubert factors are not the only ones a court may consider, and the fact that the doctor’s opinion does not meet one of the criteria does not necessarily result in exclu- sion of the testimony. The lack of peer review or publication will not preclude admissibility if the doctor’s opinion is supported by widely-accepted scientific or medical knowl- edge. The fact alone that a physician has extensive medical training and several board certifications in specialty areas will not make his or her opinion legally admissible or reliable if the rest of the doctor’s peers do not accept that opinion as mainstream. The physician’s specialties may make him or her qualified as an expert, but do not make the medical opinion on causation admissible. In the Daubert case, the plaintiff’s attorney sought to prove that Bendectin taken during pregnancy caused birth defects. There were eight experts prepared to testify that Bendectin taken during pregnancy both can (general causa- tion) and did (specific causation) cause the child’s birth defects. The Plaintiff sought to prove the causation using in vitro, animal, and epidemiological studies. The U.S. Supreme Court did not rule on the admissibility of the physician’s opinions, but did establish the guidelines for federal courts in determining the relevancy and reliability of such medical opinions and scientific evidence. Frequently, the state of medical/scientific knowledge and research has not advanced far enough to warrant widespread acceptance. The fact that the doctor feels passionately about the medical evidence is not sufficient for the court to accept