Just how bad an idea is the plan by the mayor of New York, Michael Bloomberg, to limit the size of sugary-drink cups (okay, pails? Buckets? Delivery devices?) to 16 ounces?

Even the big-government left is lining up against the proposal.

The Democrat who is speaker of the New York State Assembly, Sheldon Silver, told the New York Post, "We may be getting too close to Big Brother….I just think we ought to step back and look at the freedoms that we have been given in this country and reflect on them."

The former governor and attorney general of New York, Eliot Spitzer, a Democrat, who wasn't shy about using his powers against Wall Street banks and insurance companies, said on television, "This I just don't think works," and framed the issue as "Come on guys, let me lead my life."

Donna Brazile, vice chair of the Democratic National Committee, said on ABC News's This Week program that "Obesity is a national problem. I don't think you can solve it by banning one of many sugary things out there. And besides, people will just cross over the Hudson and get a Big Gulp over there."

USA Today, not usually a font of libertarianism, had an editorial declaring "Bloomberg's plan is short on logic and long on intrusion," and asking, "what's next? Will New York, home to the towering corned beef sandwiches, soon allow them to be piled only 3 inches high?" The New York Times ran its own editorial opposing the ban, describing it as "overreaching" and "too much nannying."

On "The Daily Show," Jon Stewart mocked what he called "a terrible idea" that "combines the draconian government overreach people love with the probable lack of results they expect."

Before tilting back that lemonade and toasting the common sense of Eliot Spitzer, Donna Brazile, and the New York Times editorial writers, though, it's worth pausing to examine just how we got here.

It's President Obama's fault.

That is not to absolve Mayor Bloomberg of all responsibility — we'll get to him in a moment. But Bloomberg resorted to his portion-control power play only after the Obama administration, after ten months of deliberation, rejected an earlier, more sensible, Bloomberg plan to prevent food stamp recipients in the city from using the Supplemental Nutrition Assistance Program benefits to pay for soda or other sugary drinks.

It's Mayor Bloomberg's fault, too. More precisely, the whole episode is an example of how Bloomberg's vast wealth, while a great political advantage, is also a liability. The fortune works in Bloomberg's favor because it conveys the impression that he "can't be bought." It also helps pay for direct mail, campaign commercials, and other election-influencing tactics that increase Bloomberg's clout. But the mayor's money also can serve to exacerbate the "yes-man" dynamic that can be an unfortunate feature of boss-subordinate relationships even when the boss isn't independently wealthy.

In this case, Bloomberg could have been saved a lot of embarrassment by having an aide with the stature and independence to tell the mayor that his idea was ridiculous before it was announced. But when the boss has the power to bestow a $400,000 bonus on a deputy mayor for campaign advice, as he did on Patricia Harris, or to install another deputy mayor, Daniel Doctoroff, as the president and CEO of his privately held financial information company, what underling is going to jeopardize a potentially lucrative future by saying "no"?

Friends who have gone to work for big grant-giving foundations have told me that all of a sudden, everyone laughs at their jokes. Bloomberg suffers from the same bubble-effect threefold — as the mayor, as a major philanthropist, and as a rich and successful businessman.

Bloomberg can try to adjust for his wealth and power by encouraging his staff to stand up to him when they think it is appropriate, the same way that even the lowliest Toyota employee can stop the assembly line if there is a problem. But the most dangerous effect of Bloomberg's wealth is not on the mayor's staff, but on his own personality. It breeds arrogance rather than humility. It doesn't have to be that way; there are plenty of humble rich people and plenty of arrogant politicians who are not rich.

But imposing this regulation — which, the New York Times reports, applies to sweetened coffee but not to Venti cappuccinos, to "delis" but not "convenience stores" — is an act of arrogance, not only when it comes to the confidence in the ability to draw such apparently arbitrary distinctions, but when it comes to the role of government.

New Yorkers love energetic and ambitious politicians. If Bloomberg had confined himself to reforming New York's public education system by expanding charter schools, to bringing the city's crime rates to record modern lows with intelligent policing, and to rebuilding the city after September 11, 2001, and the financial crisis with a pro-business tone, he might go down in history as one of our greatest mayors. Now, he risks being remembered as a laughingstock: the scourge of the Big Gulp, the mayor who, in trying to teach self-control to obese New Yorkers, neglected the same virtue of restraint when it came to the use of his own public power.

Ira Stoll is editor of FutureOfCapitalism.com and author of Samuel Adams: A Life.