Montana Governor Greg Gianforte signed a law stating that "sex" can only be defined as male or female based on a person's "biological and genetic indication" at birth:
Sex means the organization of body parts and gametes for reproduction in humans and other organisms. In humans there are exactly two sexes, male and female, with two corresponding types of gametes. Sexes are determined by biological and genetic indication.
Female sex: XX - male sex: XY
The law establishes that a person with female sex is a person who has XX chromosomes and produces eggs:
A member of the human species that, under normal development, has XX chromosomes and produces or would produce relatively large, relatively immotile gametes or eggs during its life cycle and has a reproductive and endocrine system oriented around the production of those gametes.
Male sex is defined as a person who has XY chromosomes and produces sperm:
A member of the human species that, under normal development, has XY chromosomes and produces or would produce small, motile gametes, or sperm, during its life cycle and has a reproductive and endocrine system oriented around the production of those gametes.
The bill was amended several times to add intersex persons, those born with a discrepancy between their internal and external organs and genitalia:
An individual who would otherwise fall within this definition, but for a biological or genetic condition, is female. An individual who would otherwise fall within this definition, but for a biological or genetic condition, is male.
It is not possible to change the "biological sex"
Carl Glimm - sponsor of the bill - stated before the House Judiciary Committee that "from a legal point of view, sex and gender do not mean the same thing." He further argued that a person's biological sex cannot be changed:
