In August 2020, Wynn joined the majority in G. G. v. Gloucester County School Board. In a 2-1 decision, the court ruled for Gavin Grimm, a transgender man who had sued the Gloucester County School Board in Virginia who had prohibited him from using the boy's bathroom. Judge Henry Floyd wrote for the majority that “At the heart of this appeal is whether equal protection and Title IX can protect transgender students from school bathroom policies that prohibit them from affirming their gender. We join a growing consensus of courts in holding that the answer is resoundingly yes.” Judge Wynn, concurring, wrote "In particular, the Board’s classification on the basis of “biological gender”—defined in this appeal as the sex marker on a student’s birth certificate—is arbitrary and provides no consistent reason to assign transgender students to bathrooms on a binary male/female basis. Rather, the Board’s use of “biological gender” to classify students has the effect of shunting individuals like Grimm—who may not use the boys’ bathrooms because of their “biological gender,” and who cannot use the girls’ bathrooms because of their gender identity—to a third category of bathroom altogether: the “alternative appropriate private facilit” established in the policy for “students with gender identity issues.” That is indistinguishable from the sort of separate-but-equal treatment that is anathema under our jurisprudence. No less than the recent historical practice of segregating Black and white restrooms, schools, and other public accommodations, the unequal treatment enabled by the Board’s policy produces a vicious and ineradicable stigma."