the failure to repair this condition or to warn the tenants about this condition, all of which contributed directly to Cayetano’s losing his footing, his subsequent fall into the railing, and ultimately, his fall to the sidewalk. Rule 702 of the Rhode Island Rules of Evidence provides that expert testimony is permissible “[i]f scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of fact or opinion.” This Court has held that “expert testimony is required to establish any matter that is not obvious to a lay person and thus lies beyond common knowledge.” Mills, 824 A.2d at 468 (<HOLDING>); see also Broadley v. State, 939 A.2d 1016,
holding expert testimony necessary to establish the existence of a causal relationship between a particular toxin and its effect on the human body recognizing the existence of the special relationship holding that to show a causal connection the plaintiff must demonstrate a relationship between the misconduct and the plaintiffs injury holding that existence of partnership depends upon the conduct intention and relationship between the parties though no one factor is determinative it is necessary to examine the  relationship as a whole holding that expert medical testimony was not necessary to establish negligence where surgeon left a needle in the patients body but stating that proof of proximate cause requires some expert testimony in medical malpractice cases