Section 18.001 After Ortiz: A New Counter-Affidavit Framework

The Texas Supreme Court’s decision in Ortiz v. Nelapatla (May 1, 2026) reshapes how counter-affidavits operate under Section 18.001. In short, a partial counter-affidavit no longer knocks out the whole medical-cost affidavit. The uncontested charges still go to the jury, and where a counter-affidavit states what amount is reasonable, it creates a floor and the plaintiff may offer that counter-affidavit itself as evidence of that amount.

Tatia Ortiz claimed injuries from a low-speed collision in a Target parking lot and sued for her medical expenses, supporting them with Section 18.001 affidavits from three providers. The defense served two counter-affidavits, each challenging only part of what a provider had billed: a billing expert contended the imaging charges ran somewhat above the usual and customary rate, and a chiropractor disputed the necessity of some of the rehabilitation services. The trial court treated those partial challenges as all-or-nothing, excluded both affidavits in their entirety, and the jury awarded Ortiz only the single bill no one had contested — about $2,200 of the roughly $19,875 she had claimed. The court of appeals affirmed. The Supreme Court reversed.

Here is how it now works. When a counter-affidavit identifies an alternative “reasonable” figure, as most typically do,  it concedes that some amount was appropriate. For example, if a counter-affidavit states that a provider’s $8,400 charge is excessive and that only $4,200 is reasonable, Plaintiffs may now use Section 18.001 to offer the defendant’s counter-affidavit into evidence and establish the $4,200 as a reasonable charge. That number now becomes admissible evidence for the plaintiff. The figure stated in a counter-affidavit functions, in effect, as a floor.

The companion point is that serving a counter-affidavit no longer renders the plaintiff’s billing affidavit inadmissible. It affects only the specific charges actually controverted, not the affidavit as a whole. The uncontested portions remain admissible and can still establish reasonableness and necessity without live expert testimony. If a counter-affidavit challenges only one provider’s charges for a particular procedure, the rest of the plaintiff’s bills survive untouched. The plaintiff then has two ways forward on the challenged charges – either (1) redact the controverted line items and submit the rest through the affidavit, or (2) rely on the counter-affidavit to establish the reasonable amount it conceded. Either way, a partial challenge no longer forces the plaintiff’s to bring an expert live.

Because Ortiz interprets the existing statute rather than amending it, this is effective immediately and governs every pending case, including matters already in suit and set for trial in the coming months, regardless of when the case was filed.

This remains the governing framework for the foreseeable future but something to watch as we move into the 2027 Legislative session.

Because the “reasonable” figure stated in a counter-affidavit is now evidence a plaintiff can use, the amount conceded deserves careful thought, and a challenge limited to price alone leaves necessity and every uncontested charge intact. It would not be surprising to see the practice move toward broader counter-affidavits, supported by a treating physician, that address the necessity of care and not only the reasonableness of a charge.