Castro was behind the sixth International Lesbian, Gay, Bisexual, Trans and Intersex Association for Latin America and the Caribbean Regional Conference held in Cuba earlier this year.
The proposed update to Cuba's expansive labor code included explicit protections based on sexual orientation. However, Castro said that because it didn't also specify protections for people based on their gender identity and HIV status, it was inconsistent with her beliefs.
It is thought to be the first time that a government bill has been voted against.
However, according to LGBTI News, Baruch College Latin American studies professor Ted Henken said that Castro’s vote “is more a sign of what Mariela can get away with than a sign of what your everyday parliamentarian can get away with.”