BOSTON – A Massachusetts town’s bylaw against public profanity appears to violate constitutional free speech rights and should not be enforced, the state’s attorney general said in a recommendation Tuesday.

Middleborough, a town of about 23,000, received national attention in June when residents at a town meeting voted 183-50 to approve an article that allowed police to enforce a 1968 bylaw by imposing a $20 fine against loud and obscene language. Supporters of the measure said it was meant to discourage groups of foul-mouthed youths who congregated on downtown streets or public parks.

The article was reviewed by Attorney General Martha Coakley’s office, which said in Tuesday’s ruling that the enforcement mechanism itself — the $20 fine — did not violate state or federal law.

“However, we have determined that some of the underlying bylaws passed more than 30 years ago no longer meet constitutional standards and those bylaws should be repealed by the town, and in the meantime, not actively enforced,” said Emalie Gainey, a spokeswoman for Coakley.

The attorney general specifically urged repeal of the 1968 bylaw barring “profane” language in public, saying it would violate First Amendment guarantees.

Coakley also recommended the town consider changes in two other bylaws — a 1972 measure against the making of an “alarming or tumultuous noise,” and a 1927 bylaw that prohibited, among other things, throwing snow balls or playing football on a public street.

Mimi Duphily, a former town selectwoman who pushed for the fine against swearing, strongly defended the town’s crackdown on profanity.

“This has nothing to do with freedom of speech,” Duphily said. “This is about verbal assault.”

The torrent of loud and abusive language, she said, would keep customers away from downtown businesses and was frightening to seniors and young children.