P was seriously injured in an accident. P sued D, alleging that his negligence caused P to suffer severe and permanent injuries and to incur past and future medical expenses. Ps deposed one of P's treating physicians, neurosurgeon Vaughn Allen, M.D. He testified that all of P's medical bills, including those from his clinic and those from P's other medical providers (hospitals, physical therapists, radiologists, etc.), were reasonable and necessary to a reasonable degree of medical certainty. Prompted by a holding in the West case (that the amount of the full, undiscounted charges billed to the patient is 'unreasonable' as compared to the amount of the discounted bills paid by the insurer). Ds filed a 'Motion in Limine to Exclude Evidence of Unreasonable Medical Charges.' Ds reasoned that P's undiscounted medical bills must be excluded because the amounts of those bills are, as a matter of law, unreasonable. According to Ds' calculations, P's health insurer paid only $18,255.42 to satisfy the medical bills. Ds contend the full charges reflected in P's medical bills are irrelevant and should be excluded on that basis. Ds argued that 'evidence of payment of the medical expenses by medical insurance will not be used to show that the medical expenses have been paid in an attempt to mitigate the damages. Rather, the evidence would be used to show whether the charges are reasonable. Ds argued that, if the full, undiscounted medical bills are admitted into evidence, then the discounted amounts accepted by the medical provider should be admissible to rebut the Ps' expert testimony that the undiscounted charges are reasonable. The trial court agreed with Ds and excluded evidence of the full, undiscounted medical bills. P sought permission for an interlocutory appeal from the trial court's order. Permission was granted by both the trial court and the Court of Appeals. The Court of Appeals reversed. It concluded that the West case did not apply to personal injury cases. It then addressed the evidence that would be permissible on remand to rebut Ps' expert testimony that the undiscounted medical bills represented reasonable medical expenses. Ds are permitted to offer proof contradicting the reasonableness of the medical expenses and the collateral source rule does not bar evidence of discounted amounts so long as that evidence is 'introduced without referencing insurance.' The Court of Appeals reversed the trial court's grant of Ds' motion in limine and held that P's full, undiscounted medical bills were admissible to prove her reasonable medical expenses resulting from the accident. It indicated that evidence of the discounted amounts accepted by P's medical providers is admissible to rebut Ps' proof that the undiscounted medical bills are reasonable, so long as insurance is not mentioned. D appealed.