If there's one labor issue that's come to the forefront of political agendas over the past few years, it's the minimum wage: Cities and states around the country are taking action to boost worker pay.

But a new wave of reform is in the works. Instead of how much you earn, it addresses when you work — pushing back against the long-standing corporate trend toward timing shifts exactly when labor is needed, sometimes at the very last minute.

That practice, nicknamed "just-in-time" scheduling, can wreak havoc on the lives of workers who can't plan around work obligations that might pop up at any time.

Following the passage of landmark legislation in San Francisco, bills have been offered in Indiana, Maryland, Massachusetts, Minnesota, Illinois, Connecticut, ­California, New York, Michigan and Oregon. Along with new proposals to expand paid sick pay, they are a bid to give employees more control over how they spend their time.

"These scheduling reforms are getting really popular, because it makes no sense that, for example, you're required to be available to work by your employer and you're not picked for that time," says Tsedeye Gebreselassie, a senior staff attorney at the National Employment Law Project. "People who don't suffer these abuses already understand what it's like to juggle work and family, so ­people really identify with that as being a problem."

In the District of Columbia, community groups and unions are formulating a bill that will address the problem of schedules that can be both shifting and inflexible. The legislation hasn't been hammered out yet, but the labor-backed group Jobs With Justice says it will likely include a requirement that employers provide workers with notice of their schedules a few weeks ahead of time, and that additional hours go to existing employees, rather than spreading them across a large workforce.

"The one thing we're finding overwhelmingly is that people aren't getting enough hours to make ends meet," says Ari Schwartz, a campaign organizer at D.C. Jobs With Justice, which is now tabulating the results of a survey of hundreds of hourly workers in the city on scheduling issues. "People aren't getting their schedules with enough time to plan child care and the rest of the things in their lives."

Twenty years ago, ­schedules weren't as much of a problem. Working in retail, especially, tended to be a solid 9 to 5 job.

But then retail hours grew longer. And then came computerized scheduling, which allowed employers to best fit staffing to demand. Here's what that looks like in practice: Handing out schedules based on what times of day or the month you expect the most business, splitting up hours across a large workforce that's available on a moment's notice and sometimes sending people home if traffic is slow.

That helps companies ­optimize their labor costs, but it wreaks havoc on the lives of low-wage workers, who don't know how much they're going to make from week to week, and often can't schedule anything else around work.

After complaints, Whole Foods rolled out a new system that allows employees to see their schedules for two weeks in advance and prevents managers from changing them at the last minute or scheduling "clopenings" — both closing the store and opening it in the morning — without an employee's consent. The ­policy has been in place nationwide since early April.

Wal-Mart has also introduced a system of "open shifts," which allows workers to pick their own hours. Starbucks curbed some of its practices in the wake of a New York Times article last year that described their effect on one barista. The Gap is working with the Center for WorkLife Law at Hastings College of Law and the University of California, San Francisco to set up pilot projects around the country that would measure the impact of giving employees stable schedules and more hours. Many companies haven't considered how much their scheduling practices are actually costing them in the form of employee turnover, says Joan Williams, a UC law professor.

"If you don't count that cost, it disappears. The idea is to generate the kind of rigorous data that will be needed to persuade people to change their financial models," says Williams. "Our hypothesis is that if you provide people with more stable schedules, you'll see lower turnover and absenteeism and higher worker engagement."

And now, there's legislation to benchmark against. Last year, San Francisco became the first jurisdiction to pass comprehensive scheduling reform, with a set of companion bills that require "formula retailers" (i.e., large chains) to give workers two weeks notice of their schedules, pay workers for the shifts when they're on call and give hours to current employees instead of hiring more, among other provisions. The law went into effect in January, but won't be enforced until July.

A bill introduced in Congress last summer would require employers to make schedule accommodations for health or child care needs, unless there is a "bona fide business reason" for denying it. And another bill, proposed last month, would prevent employers from firing workers for requesting a schedule change.