Walter Olson of the Cato Institute shares with Commentary readers the significance of a judge’s decision to strike down New York City Mayor Michael Bloomberg‘s soda restrictions.

In the short term, Judge Tingling’s decision is a delicious win for consumer liberty against the Napoleonic New Bossiness streak in the city’s chief executive. As has been pointed out, however, the judge would not necessarily have struck the regulations down had they been adopted by the New York City Council rather than imposed by the mayor’s appointees through administrative fiat; he wasn’t recognizing any general right of individuals to decide for themselves what foods to consume. Moreover, the judge’s diagnosis of the rules as “arbitrary and capricious” because they were riddled by so many exceptions is at best double-edged from opponents’ standpoint; would we really prefer rules redrafted so as to allow fewer exceptions?

But [the] decision should cheer us for other reasons. It holds the Gotham administration accountable for overstepping the separation of powers, an important principle in the safeguarding of liberty. (In a profile of Judge Tingling, the New York Times notes that he’s been skeptical of government claims to power in a number of other cases as well.)

Under separation of powers as generally understood at the time of the Framers, an executive agency cannot enact new legislation on its own, that being a role constitutionally reserved for the legislature. Especially during the Progressive Era and New Deal, these barriers were eroded as administrative agencies claimed a power to issue regulations that looked more and more like traditional legislation, under powers deemed to have been delegated by the legislature. Still, there are some limits, both under the U.S. Constitution and in New York (which under a 1987 case called Boreali v. Axelrod applies its own, quirky standard in evaluating whether a regulation oversteps the separation of powers.) And those limits to delegation were at the heart of the soda case.