Lay Witnesses Can Testify on Causation, but Experts Needed for Reasonableness of Bills. In a personal injury action, medical bills are admissible only if they meet a multi-part test. First, obviously the bills have to be causally related to the defendant’s negligence. This fact may sound obvious, but is often disputed or improperly alleged by plaintiffs. A lay witness just like the plaintiff in Thomas can testify that medical care was obtained because of an accident to satisfy causation. In re: Gloria T., 73 Md. App. 28, 33, 532 A.2d 1095, 1097 (1987). In the latter case, the parent of the victim testified that shortly after the attack she took the victim to the local hospital’s emergency room for treatment. The court held that that sufficient proof to prove a causal link between the attack and the subsequent medical care. Gloria T., 73 Md. App. at 31, 532 A.2d at 1096. Secondly, the bills have to be reasonable. Thomas v. Owens, 28 Md. App. 442, 445, 346 A.2d 662, 664 (1975) (citing cases). In Thomas, the Court noted: In Maryland, before a medical bill can be admitted to prove the reasonableness of the amount charged, there must be other evidence that the charge set forth in the bill was reasonable. Thomas, 28 Md. App. at 445, 346 A.2d at 664. Expert testimony is required to establish reasonableness. Thomas, 28 Md. App. at 451, 346 A.2d at 667. Therefore, a lay person such as a victim’s parent cannot establish the reasonableness of a bill. Finally, the bill has to overcome hearsay objections. The traditional way was cumbersome requiring a live witness to testify at to foundation and authenticity of the bill. Today a certificate of business records as laid on in the Maryland rules will allow the hospital bill to be admissible as an exception to the hearsay rule under the business records statute. It is common knowledge that hospitals regularly submit invoices to patients for the services rendered, and the invoice in question was issued by a government agency pursuant to a statute authorizing recovery from Thomas of the reasonable value of medical services rendered Owens. Following each of these steps is necessary to ensure bills are admitted into evidence. Remember, if the bills are not in evidence the jury cannot consider them as part of their deliberations.