HELENA, Mont. — A Montana judge on Thursday temporarily blocked enforcement of a law that required transgender people to have undergone a “surgical procedure” before being allowed to change their sex on their birth certificates. The law was part of a growing list of Republican-controlled states including Alabama that have moved to restrict transgender rights as they gain more visibility in culture and society. In Montana, District Judge Michael Moses of Billings ruled the law is unconstitutionally vague because it does not specify what surgical procedure must be performed. The law also required transgender people to obtain a court order indicating they’d had a surgical procedure. Because he could grant the temporary injunction based on the vagueness issue, Moses said he did not further analyze the constitutionality of the law.