In 2008, Washington joined San Francisco in creating a law requiring private businesses in the city to provide paid sick days to their employees. Unlike San Francisco, D.C.'s city council wisely exempted tipped employees and others for whom the law could create unintended consequences.

Later research would prove this to be a prescient move: A survey in San Francisco following passage of that city's law -- a survey published by sick-leave advocates, no less -- found that nearly 30 percent of the lowest-paid employees reported reduced hours or layoffs at their place of work.

Despite these warning signs, D.C.'s unions and activist groups have continued to pine for a broader law that does away with pesky exemptions: Witness their recently proposed sick-leave "audit," a thinly veiled attempt to have the D.C. Council put its stamp of approval on a plan to expand the mandate. Though council members Jim Graham and Phil Mendelson have voiced support, it's a bad idea that will ultimately lead to unfortunate consequences.

The campaign to expand Washington's law kicked off last December in a meeting at the Vermont Avenue Northwest headquarters of the SEIU Local 32BJ. There, the D.C. Restaurant Opportunities Centers United, the Employment Justice Center, and Jews United for Justice -- all labor-aligned groups -- rolled out a plan for an "earned paid sick leave" campaign focused on restaurant employees.

In the months that followed, the campaign started a website and began collecting signatures in support for its efforts from like-minded residents in D.C. More recently, the George Washington University-affiliated Institute for Women's Policy Research -- the country's leading purveyor of activist-friendly "research" on sick days -- brought attention to the campaign by releasing a briefing paper advising a comprehensive audit of the law. The institute repeatedly offered up its own work as an example of what might be done.

Of course, we don't need to wait for months to determine what an IWPR-assisted audit of the city's sick leave law would find. Every cost-benefit analysis released by the organization has reached the same predetermined conclusion: Sick day mandates are a win for employers and employees, and employers can actually save money following the mandate's passage. (It makes you wonder why businesses have waited so long to start offering a paid policy.)

That's not to say the institute's claims are credible. Its cost-benefit analyses project millions of dollars in employer savings from a reduction in employee turnover -- despite the fact that surveyed employers in San Francisco didn't report that as a benefit. One employer pointed out the obvious: If everyone's mandated to give the benefit, there's no incentive to stick with one business over another.

And the IWPR isn't above downplaying inconvenient results about purported public health benefits. In its San Francisco report, for instance -- where survey results suggested that the law had very little impact on the number of sick employees in the workplace -- the institute buried the problematic numbers in an appendix table.

That a sick day mandate would have unintended consequences in certain industries is not surprising. Rather, it's a natural consequence of basic business realities in places like the food industry, where employers keep just a few cents in profit for each sales dollar and can't always pass off new labor costs through higher prices. A new benefit mandate will force some to slash employee work hours or other benefits to maintain a narrow profit.

Progressive activists have never much cared for the laws of economics, and there's no doubt that they'll push ahead with their strategy to flack the sick leave law -- and sell lawmakers on how much more effective it would be if expanded. But that doesn't mean council members need to take part in this charade.

Michael Saltsman is a research fellow at the Employment Policies Institute.