In this new ear of cheap fuel, resistance to the EPA's "boutique fuel" requirements — which stipulate a unique recipe for fuel sold in a particular state — has quieted. The regulators can breathe a sigh of relief for now.

But what are these "boutique fuel" requirements? What is their purpose? And are they more hassle than they are worth?

You may have not heard of boutique fuels. But they were once been deemed relevant enough to warrant their own Boutique Fuels Task Force, launched by President George W. Bush in 2006 when global oil prices were on the ascent.

The logic behind their existence is that while crude oil is seen as a global commodity, the more complex reality is that not all fuels are created equal, as I have pointed out in a previous post. Neither are their carbon emission profiles.

Boutique fuels are unique localized blends of fuels that are permissible for sale in different states. Until 1990, there was a relatively small menu of fuels from which sellers were able to choose, and the gasoline market was broadly a single national one. However, in a quest to improve air quality, states soon latched onto fuel standards as a way to meet the National Ambient Air Quality Standards (NAAQs) required by the EPA under the Clean Air Act, which was passed in 1963 and radically amended in 1990.

Ozone conditions, fed by pollutants, vary across the country. California — where the geography of the Central Valley has an unfortunate habit of attracting a shroud of smog — has led the way by imposing more severe requirements for RFG than the rest of the country (RFG is an "environmentally friendlier" version of gasoline, supplemented with fuel oxygenates that reduce harmful byproducts of carbon monoxide).

That is how we arrived where we are today. A blend processed for California cannot simply be diverted to Louisiana or any other state. A state cannot just "borrow" fuel from a neighbor to stave off shortages.

There is even seasonal variation, in the form of "winter fuels" and "summer fuels," because ozone concentrations increase in colder months. It also helps to answer the complaints of disillusioned Californians over why historically low gas prices have not reached the West Coast yet.

One of the major concerns of these constraints on gasoline sales is the potential for volatility. In the event of a supply chain crisis, distributional inflexibility enforced by the regulators could result in shortages of the correct "recipe" and localized price spikes. But experience has shown that waivers of the legislation do their job.

One of the potentially far-reaching economic impacts of hurricanes Katrina and Rita in 2005 was the temporary shutdown of most crude oil and natural gas production in the Gulf of Mexico, as well as much of the refining capacity in Louisiana and Alabama. Along with releases from the Strategic Petroleum Reserves, the regulatory tweak of waiving the boutique fuel requirements saved residents from a dramatic price spike.

Rightly or wrongly, these state fuel regulations have been blamed in the past for raising prices at the pump, threatening to revive the politically sensitive issue of the cost of driving. It has provoked outrage from politicians intent on capturing the motorist vote by attacking the regulations — particularly in an era where the EPA has become a prime target for Republican governors.

In today's much looser global oil markets, that outrage has disappeared from the headlines. The data is so far unclear on the impact of boutique fuels — conservative commentator Steven Hayward calls for its abolition, arguing it has delivered only marginal benefits and is a "perfect case study in bureaucratic inertia and industry rent-seeking." Others refute that.

However, one thing is for sure: Once-hot topics can rapidly drop off the political agenda, and the drafters of EPA reports on the subject can probably afford to take their foot off the pedal until price signals change.