"The dynamics of the petroleum system are such that it is virtually impossible to identify where gas is coming from," he says. "It is extraordinarily difficult to know what country a crude oil came from, to start with, once it goes to the refineries. And once it leaves the refineries, it's quite difficult to say what refinery made that."
Droitsch, who termed the labeling a "first step," was skeptical.
"Often we've seen industry cry wolf when it comes to something as simple as tracking fuel, and I would question that argument," she says. "People have the right to know what is going into their fuel tank."
Corrected on : Update 1/23/14: This story has been updated to include a quote from Matt Dempsey. Clarification 1/24/14: Dempsey's identification has been clarified to more accurately reflect for whom he was speaking.