Low-wage retail workers across the United States struggle with unpredictable work schedules and involuntary part-time employment. Now, one major American city appears poised to ensure that those concerns are given legal voice.

The Board of Supervisors in San Francisco, California, unanimously approved two pieces of legislation on Tuesday collectively known as the Retail Workers Bill of Rights. If made law, the bills would financially penalize chain retailers (defined as “formula retail” establishments under municipal law) that assign employees erratic work schedules. They would also extend additional workplace protections to part-time retail workers.

The board is required to vote on the legislation twice before sending it to Mayor Ed Lee for his signature. The second vote is scheduled for Nov. 25.

At least one of the bills’ provisions has a precedent: The $15 minimum wage legislation recently passed in SeaTac, Washington. Much like the SeaTac bill, the Retail Workers Bill of Rights mandates that employers offer any additional work hours to part-time employees before pursuing new hires. If passed into law, San Francisco would become the first large U.S. city to adopt such a measure, as well as the first to take significant action against unpredictable scheduling in the retail sector.

The labor coalition Jobs with Justice San Francisco estimates that as many as 40,000 San Francisco workers could be affected by the proposed legislation.

“People are really starting to recognize that this issue of not having advance notice of your schedule is a problem, because it means you can’t plan your life, you can’t plan for childcare. Or, if you’re going to school, you can’t plan your classes,” said Tsedeye Gebreselassie, a staff attorney for the National Employment Law Project. “If you have to take on a second job … you can’t plan those hours.”

The proposed legislation would require that chain retailers provide schedules to workers at least two weeks in advance. Workers would also be entitled to additional pay if their schedules change at the last minute.

Local business groups, including San Francisco’s Chamber of Commerce, oppose the legislation, arguing that it doesn’t allow sufficient flexibility to employers who may experience seasonal shifts in what they need from their employees.

“Many formula retailers are in fact very small independent franchisees that have limited human resources capabilities and few employees to cover shift changes,” wrote Jim Lazarus, the Chamber’s senior vice president of public policy, in a Nov. 13 memo to members of the Board of Supervisors. “Basically, they do not have the flexibility to comply with these proposed mandates.”

While Mayor Lee has not publicly said whether he supports the proposed legislation, Gordon Mar, executive director of Jobs with Justice San Francisco, told Al Jazeera he is confident the votes are there to override a possible mayoral veto.

If the Retail Workers Bill of Rights becomes law – with or without mayoral consent – then it will be the latest in a series of victories for Jobs with Justice San Francisco. Just weeks earlier, city voters approved a Jobs with Justice-backed ballot measure raising the city’s minimum wage to $15 per hour. The coalition has also successfully organized on behalf of paid sick-leave legislation and employer-provided health care, among other measures.

“There’s a really strong community of progressive and labor groups that have worked in coalition to lead these campaigns,” said Mar. Once the campaign for the Retail Workers Bill of Rights has concluded, he said, the coalition’s next big push would likely involve using provisions of successful legislation they helped pass to enable “new organizing with restaurant and retail workers in our city.”

There’s some urgency to the campaign, as San Francisco – despite its progressive reputation – remains one of the most unequal cities in the nation. A recent study by the city’s Human Services Agency found that San Francisco is about as unequal as Rwanda by one measure of income inequality. That’s in large part due to the city’s disproportionately large share of multi-millionaires, its dwindling middle class and unusually high cost of living.