Leaders of the seven most advanced economies in the world are meeting in Germany this week. The discussions have been dominated by Russia and the war in Ukraine. How to cut the price down on Russian oil was a major discussion Sunday. Leaders are looking to establish a cap on Russian oil prices. This would effectively create an oil buyers’ cartel, though nothing has been set in stone yet. Gregory Brew, who studies energy policy at Yale University, says there’s a number of stumbling blocks in front of this idea.