Lawmakers on Thursday will debate the bill, which has the strong support of Democratic Senate President Stan Rosenberg.
Rosenberg has said it will help prevent discrimination in restaurants, malls and other public locations.
The bill would also let transgender people use bathrooms that correspond with their gender identity.
Opponents say the bill would violate the privacy rights of girls and women.
Massachusetts Family Institute President Andrew Beckwith says women and children will have no protection against being exposed to naked men in locker rooms if the bill passes.
Rosenberg says the bill wouldn’t bring an unwanted male presence into women’s rooms. He says transgender men are men and transgender women are women.
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