When 41-year-old Jehanne, a lesbian, was repeatedly insulted for supporting LGBT rights during a tram ride in the Swiss city of Geneva last month, she threatened to call the police.

But her aggressor said his remarks were not a crime under Swiss law. "I was shaking, I was crying too," said Jehanne, an artist and mother of an eight-year-old boy, who asked for her last name to be withheld. "I looked around me and I was really surprised that no one looked at me or intervened at all."

In his response to Jehanne, her aggressor was strictly correct, exploiting a Swiss loophole in lesbian, gay, bisexual and transgender (LGBT) rights. Conservative Switzerland, unlike many of its western European neighbors, does not have yet have laws that specifically protect lesbians, gays and bisexuals from discrimination.

The government hopes to change that. Parliament passed a law in 2018 to extend anti-racism statutes to cover sexual orientation, and offenders could be jailed for three years. But opponents last April obtained the minimum 50,000 signatures necessary under Switzerland's system of direct democracy to put to the matter to a vote, to be held on Sunday.

"I trust the Swiss people will not let themselves be censored," said Marc Früh, a member of the small Federal Democratic Union (EDU) party, which launched the referendum. His party, which has a Christian base and is stronger in the German-speaking east, has placed posters around the country showing a blonde woman with bulging eyes and black tape forming a cross over her mouth.

Supporters of the law have countered with images of two pink hearts rubbing up against each other beneath an umbrella - a symbol Jehanne was wearing on a pin the day she was verbally assaulted. Caroline Dayer, an expert in preventing violence and discrimination, said attacks on gays, already common, had increased as the vote has stirred emotions. In Switzerland, two-thirds of lesbians and 80% of gay men are targeted at some point in their lives, she said.

The government stresses that the new law will not hinder public debate or affect private conversations. Even jokes about gays are still OK "as long as they respect human dignity", Interior Minister Alain Berset said in a video message to voters.

Opinion polls suggest opponents do not have enough backing to scupper the new law, with 65% inclined to vote yes, according to Swiss broadcaster RTS. Even so, the law's supporters say Switzerland still trails most neighbors on LGBT+ rights. The protections under the new law do not apply to gender identity, for example, meaning transgenders are excluded.

Mathias Reynard, a Socialist MP who first raised the need for homophobia protection in 2013, hopes to bring Switzerland in line with 18 other European jurisdictions on gay marriage and a debate is planned next month. Civil unions are already legal. "I hope one day we won't need all of this (protection)," said Jehanne. "But I have the impression it won't be the case any time soon."