The ‘Yale Report’ Against the Cass Review: Science or a Legal Brief?

Since the publication of the Cass Review in 2024 — the UK’s four-year investigation into the evidence base for puberty blockers and cross-sex hormones in young people with gender dysphoria — advocates of the gender-affirmative model have been trying to undermine the report. The most frequently cited weapon is a paper by American legal scholar Meredithe McNamara and co-authors, including well-known gender-affirmative clinicians such as Johanna Olson-Kennedy and Jack Turban. Their piece claims the Cass Review “repeatedly misuses data” and violates its own evidentiary standards — a report that stands in the same tradition as the Dutch Dutch Protocol, which served for decades as the foundation for Western gender care and is now itself facing the same methodological criticism. The problem: that claim was never peer-reviewed, and the piece was written for a purpose other than science.

What exactly is being claimed, and by whom

The paper appeared on the website of the so-called “Integrity Project,” housed at Yale Law School. That origin gave the piece international authority: media outlets and activist organizations quickly began referring to “the Yale report,” as if the university itself had endorsed its content. That is not what happened. Yale Law School did not publish the piece as its own scholarly research; it merely hosted the platform on which McNamara and her co-authors — none of whom are affiliated with Yale as authors of the critique — posted their text. An analysis of the “Yale” claim by the Society for Evidence-Based Gender Medicine (SEGM) explains how this construction works and why the suggestion of university endorsement is misleading.

No peer review, but a role in the courtroom

The most striking fact is not the content of the critique, but its use. McNamara and several co-authors served as paid expert witnesses in more than a dozen US lawsuits concerning gender care for minors, and submitted a nearly identical version of their paper as an amicus brief to the US Supreme Court, in the high-profile case United States v. Skrmetti. In other words: the same document functioned simultaneously as supposedly independent scientific criticism and as a legal argument by authors who had a financial interest in judges taking the Cass Review less seriously. Such a dual role — author of the “scientific” rebuttal and paid witness in the cases that stand to benefit from it — would, in a peer-reviewed journal, have been flagged and weighed as an obvious conflict of interest. In an unreviewed publication on a university platform, that safeguard is absent.

What British clinicians say in response

A recent counter-analysis by a number of prominent British clinicians — directly involved in or familiar with the development of the Cass Review — concludes that the McNamara paper is not a serious scientific effort, but a document written primarily to influence US lawsuits, packaged as methodological criticism. They point out that the paper cites selectively, fails to discuss the original systematic reviews underlying the Cass Review in their full methodological context, and draws conclusions that go beyond what the data support. That is a serious accusation, and it is up to the reader to weigh the underlying sources themselves — but the pattern they expose, context and interests, is itself verifiable and is laid out below in the sources.

The BMA motion: how the Yale label influenced policy

The supposed Yale origin of the McNamara paper played a direct role when the British Medical Association (BMA) passed a motion in 2024 calling the Cass Review “unsubstantiated” and calling for its implementation to be reconsidered. Medical organizations and commentators pointed out at the time that the motion relied heavily on the authority attributed to the “Yale report” — without the underlying claims themselves having been independently reviewed. The BMA has since partly revised that position, partly because it became clearer how the paper came about and what interests the authors had in ongoing US lawsuits.

A broader pattern: consensus resting on authority, not evidence

This episode does not stand alone. Our partner site wpath.nl previously documented how a Harvard legal scholar concluded that WPATH’s own ‘medical consensus’ rests largely on politics rather than evidence. The mechanism is similar: an institution with authority — a university, a professional association — is used to lend a claim an authority it would not have on its own merits. For readers who want to follow the science and the debate surrounding gender care, that is an important signal: the question “who published this” is not the same as the question “has this been reviewed.” Our earlier article on the Dutch quality standard for transgender care showed a similar pattern: institutions with authority endorsing claims without explicitly weighing the underlying conflicts of interest.

Source versus interpretation

Important to keep in mind: the fact that the McNamara paper was not peer-reviewed and was used legally by the authors themselves says nothing definitive, on its own, about whether every individual claim in it is incorrect. It does mean that the paper does not deserve the status that the label “Yale report” suggests, and that the authors’ dual role — scientific critic and paid litigant — warrants a note of caution for anyone citing the piece as neutral science. This interpretation is our editorial team’s own; the facts about origin, funding, and litigation are substantiated with sources above.

Sources

Society for Evidence-Based Gender Medicine (SEGM), “The Cass Review, the ‘Yale’ Report, and the Importance of Keeping Special Interests at Bay,” 2026. segm.org/Cass_Integrity_Project_Yale

Yale Law School, “White Paper Addresses Key Issues in Legal Battles over Gender-Affirming Health Care.” law.yale.edu — Integrity Project white paper

Erin Reed, “British Medical Association Calls Cass Review ‘Unsubstantiated,’ Passes Resolution Against Implementation,” Erin In The Morning, 2024. erininthemorning.com — BMA resolution

Wpath.nl, “Harvard legal scholar: WPATH built its ‘medical consensus’ on politics, not evidence,” 2026. wpath.nl/artikelen/harvard-jlpp-facade-medical-consensus-wpath