Plainly, serious political and legal questions surround the effort of New York City Mayor Michael R. Bloomberg to limit the size of sugary drinks that can be sold in the city. On Monday, a State Supreme Court justice struck down the city’s limits on those drinks, calling them “arbitrary and capricious.” Bloomberg says he will appeal.

Where there can be no question, though, is in the deadly accuracy of Bloomberg’s concerns. Americans’ consumption of sugar is compromising their health, driving up public costs and even threatening national security. Obesity and diabetes are daggers at the nation’s throat. Government must play a role in responding to them.

This is a classic case of competing interests and, as with all such conflicts, the question isn’t if a line should be drawn limiting one or the other, but where the line should be drawn: At what point does government become too intrusive and when is it obliged to assert itself?

That there must be such a role is undeniable, given the nature of the threat. New research has identified sugar as the leading culprit in the nation’s rising rates of diabetes, and it identified sweetened sodas as the source of a worldwide surge in the disease. Sugar consumption and obesity also go hand-in-hand.

According to Business Insider, the annual medical costs of obesity are as high as $147 billion. Medical costs for obese people are $1,429 more than medical costs of normal weight people. What is more, the public helps pay those costs not only through Medicare and Medicaid, but through private insurance premiums that are driven up because of health problems caused by obesity.

And, perhaps most ominous of all, many military leaders, including two who served as chairman of the Joint Chiefs of Staff, have called on Congress – not a mayor, not a governor, but Congress – to pass child nutrition legislation. The reason: obesity has become the leading medical reason that recruits are rejected for military service.

In an op-ed published in the Washington Post three years ago, retired Army Gens. John M. Shalikashvili and Hugh Shelton wrote: “Our country is facing another serious health crisis … We must act, as we did after World War II, to ensure that our children can one day defend our country, if need be.”

So much for the facile protests about a “nanny state.” Those who make the easy complaint may be able to check off the “complies with doctrine” box on their ideological registration papers, but they are also doing the country a disservice. While reasonable people can argue over the proper role for government in the matter of obesity, no responsible person can deny that government has a compelling interest in the issue.

It is good that Bloomberg plans to appeal this ruling, but even if the city loses, it shouldn’t back down from engaging its citizens on a matter that affects them, their children and every city taxpayer. And while others have also taken up this cause – first lady Michelle Obama prominent among them – more voices need to be raised. Childhood obesity rates fell slightly last year, but not enough to discount the need for an aggressive response. This remains a national crisis.