This article reviews the development of common law rights in water and oil and gas to synthesize lessons for shaping the content and limits of rights in pore space. Then, applying these lessons to the current state of pore space rights, the article explains that rights in pore space are established by a default rule of prior use and are absolute, subject to little if any limitation. As demand for the resource continues to grow, however, owners and, ultimately, courts will likely search for ways to limit the absolute extent of pore space rights to avoid a tragedy of the pore space commons.
In searching for doctrinal mechanisms to make pore space rights limited, or correlative, instead of absolute, the article predicts that courts will be tempted to choose between establishing limits by strict, formalist rules of proportionality (which favor certainty), on the one hand, and instrumentalist, utilitarian standards of reasonable use (which favor development of the resource), on the other. The Article, however, identifies an underexplored doctrine from oil and gas law that would define the limits of pore space rights without resort to purely instrumentalist or formalist doctrines. The “fair-opportunity doctrine” articulated here would permit an owner to use any quantity of pore space anywhere in a common reservoir, so long as it does not interfere with the lawful existing operations of other owners, or deprive other owners of a fair opportunity to either participate in the proposed operations or conduct like operations from their respective land.