law, the “plaintiff has the burden of proving the applicable standard of care, the defendant’s failure to meet that standard, and the causal relationship between that failure and the plaintiffs injury.” Godfrey, 559 F.3d at 572. Under District of Columbia law, “if the subject in question i testimony is not always “required to establish the standard of care in cases involving supervision .... ” Godfrey, 559 F.3d at 572. Rather, “as to the need for expert testimony, the factual context matter[s].” Id. at 573. See also Daskalea v. District of Columbia, 227 F.3d 433, 445 (D.C.Cir.2000) (explaining that expert testimony is not necessary to establish negligence when the conduct at issue is “persistent, open and notorious”); District of Columbia v. Tulin, 994 A.2d 788, 795 (D.C.2010) (<HOLDING>). Specifically, the cases finding expert
holding that expert testimony should not be admitted as to a matter that is obviously within the common knowledge of jurors because such testimony almost by definition can be of no assistance holding that expert testimony is unnecessary where the case is not a case in which lay jurors would be unable to grasp the issues without expert assistance holding that jurors do not need expert testimony on matters of common knowledge recognizing that the need for the expert was so great that the decision to preclude the expert effectively amounted to dismissal of case holding that a request for funds for expert testimony must show inter alia that the testimony is crucial and is subject to varying expert opinions