In Texas, a plaintiff seeking to recover past medical expenses must prove that the amounts they paid or incurred are reasonable in order to actually recover those amounts.
Plaintiffs have one of two avenues they can take to prove that their medical expenses were reasonable. First, plaintiffs may establish their paid or incurred medical expenses are reasonable through expert testimony at trial. Second, and more commonly, plaintiffs will attempt to prove their medical charges are reasonable through the process outlined in § 18.001 of the Texas Civil Practice and Remedies Code. Section 18.001 allows a claimant to present evidence that their medical expenses are reasonable and necessary by an uncontroverted affidavit that complies with § 18.001.
In turn, a defendant can still challenge the assertion that a claimant’s medical expenses were necessary at trial. However, § 18.001 also provides defendants with a powerful means to controvert a claimant’s affidavit before trial ever starts – the counter affidavit. When a plaintiff’s § 18.001 affidavit is controverted by a defendant’s § 18.001(f) counter affidavit, the plaintiff will be required to prove their medical expenses were reasonable and necessary through expert testimony at trial, therefore increasing the evidentiary burden on a plaintiff’s recovery of medical expenses.
Counter affidavits are one of essential tools a defense attorney possesses to refute the necessity and reasonableness of a Plaintiff’s medical costs, and the Texas Supreme Court has recently clarified the hurdles that counter affidavits must clear to be admissible to the courts.

To satisfy the requirements of § 18.001(f), counter must be (1) qualified, by knowledge, skill, experience, training, education, or other expertise, to testify in contravention of all or part of any of the matters contained in the initial affidavit, (2) must be reliable, and (3) must provide reasonable notice of the basis on which the defendant intends to controvert the proffered medical expenses at trial.
In In re Allstate, the Texas Supreme Court squarely addressed the issues of when a counter affiant is sufficiently qualified, when a counter is sufficiently reliable, and when a counter affidavit gives reasonable notice of the basis of its conclusions. In re Allstate Indem. Co., 622 S.W.3d 870, 877 (Tex. 2021).
Alaniz provided affidavits indicating she had incurred approximately $41,000 in reasonable and necessary medical expenses. Allstate offered a counter affidavit from a registered nurse with over twelve years of medical billing review experience. Alaniz moved to strike the counter affidavit, arguing that it did not give reasonable notice of the basis of its conclusions and the nurse's opinions were unreliable. On both points The Supreme Court of Texas disagreed, first concluding that Dickison was qualified to testify as to the reasonableness of plaintiff’s medical charges and that Dickison’s affidavit and that the affidavit gave reasonable notice of the basis of its conclusions.
In deciding that Dickison was qualified to author the affidavit, the Court made it clear that the statute requires only that the person authoring the counter affidavit be qualified to testify about the reasonableness of the medical expenses described in a plaintiff’s affidavit.
In deciding that Dickison’s affidavit gave plaintiff reasonable notice of the basis of its conclusions, the court likened the requirement to Texas’ fair notice standard. Here, Dickison’s affidavit put plaintiff on notice of each itemized charge that was being controverted as unreasonable and provided the bases for which she challenged the reasonableness of the charges.

In the case of In Re Chef’s Produce of Houston, the Supreme Court of Texas had the opportunity to revisit the § 18.001(f) analysis it established in In re Allstate and expand on its guidelines regarding counter affidavits. Estrada provided affidavits indicating he had incurred approximately $19,000 in reasonable and necessary medical expenses. Chef’s Produce offered a counter affidavit from Dr. Sanchez, an anesthesiologist and pain management doctor who operated in the geographic region that plaintiff received medical care in. In his counter affidavit, Dr. Sanchez concluded that some of the care Estrada received was neither necessary nor reasonable. Plaintiff moved to strike the affidavit, arguing that Dr. Sanchez's counter affidavit impermissibly challenged causation.
The Supreme Court of Texas noted that § 18.001(f) states that a counter affidavit may not be used to controvert the causation element of the cause of action. However, the Court disagreed with plaintiff that the presence of a causation opinion in an otherwise compliant counter affidavit renders either the counter affidavit or the opinion invalid. The Court clarified that rather, Section 18.001(f) simply clarifies that the causation opinion is not admissible solely by virtue of its inclusion in the counter affidavit.