Over 1600 scientists have signed a letter to President Donald Trump savagely castigating him for using “pseudoscience” to justify discrimination against transgender people. Nine Nobel Prize winners are among the signatories.

“This proposal is fundamentally inconsistent not only with science, but also with ethical practices, human rights, and basic dignity,” the biologists and geneticists write.

The administration plans to narrowly define the word “gender” to write transgender people out of civil rights protections. It would radically change the legal definition to “a biological, immutable condition determined by genitalia at birth.”

Related: Trump doesn’t know about his administration’s attempt to erase trans identity

The Department of Health and Human Services is leading the charge to change the definition, arguing that court rulings and government agencies should determine gender “on a biological basis that is clear, grounded in science, objective and administrable.” Any dispute of gender would be judged through genetics testing.

“The sex listed on a person’s birth certificate, as originally issued, shall constitute definitive proof of a person’s sex unless rebutted by reliable genetic evidence,” the agency writes in a draft memo currently being circulated.

“The proposal is in no way ‘grounded in science’ as the administration claims,” the scientists write.

“The relationship between sex chromosomes, genitalia, and gender identity is complex, and not fully understood. There are no genetic tests that can unambiguously determine gender, or even sex. Furthermore, even if such tests existed, it would be unconscionable to use the pretext of science to enact policies that overrule the lived experience of people’s own gender identities.”

“Multiple standards of health care for transgender and intersex people emphasize that recognizing an individual’s self-identified gender, not their external genitalia or chromosomes, is the best practice for providing evidence-based, effective, and lifesaving care,” the scientists write.

“Given its scientific and ethical failings, we call upon the administration to withdraw this proposed policy. We also ask our elected representatives to oppose its implementation, as it would cause grave harm to transgender and intersex Americans and weaken the constitutional rights of all Americans.”

“This proposal is an attempt to put heartless restraints on the lives of 2 million people, effectively abandoning our right to equal access to health care, to housing, to education, or to fair treatment under the law,” Mara Keisling, executive director of the National Center for Transgender Equality, said when news leaked about the administration’s plans to redefine the word.

“This administration is willing to disregard the established medical and legal view of our rights and ourselves to solidify an archaic, dogmatic, and frightening view of the world.”