The last few years have seen a surge in interest in geologic carbon sequestration, also referred to commonly as carbon capture and sequestration or carbon capture and storage (CCS), as a way to reduce carbon dioxide (CO 2 ) emissions, and thereby help to address concerns about climate change. The Energy Independence and Security Act of 2007, P.L. 110-140 , contains measures to promote research and development of CCS technology and assess sequestration capacity, including a measure to clarify the framework for issuance of CO 2 pipeline rights-of-way on public land. The increased discussion of CCS technology has given rise to consideration of a number of potential legal issues related to the technology as it is currently envisioned. Among these issues are questions about legal control of the underground "pore space" used for CO 2 storage in most CCS models, questions about regulation of CO 2 pipelines, and liability concerns associated with CCS. This report discusses some of these legal hurdles that may need to be addressed if CCS technology is developed and employed. In recent years, concerns over global climate change have been at the forefront of many policy discussions. Some have suggested that recent increases in the global temperature, as well as future anticipated increases, are the result, at least in part, of emissions of large quantities of CO 2 from man-made sources. While most proposals related to climate change have focused on limiting emissions, one of the more prominent ideas to address these climate change concerns is the capture and direct sequestration of CO 2 emissions. CCS is a process whereby CO 2 emissions would be "captured" at their source and then stored or "sequestered" either underground or elsewhere, rather than being released into the atmosphere. In most models, this storage/sequestration would take place underground. CCS technology is still in the early stages of development. Therefore, there are a number of operational questions to be answered before we can fully understand all the legal issues that may arise. However, because the development of CCS technology could well depend in part upon the resolution of some of these legal issues, it is important to understand them as the discussion of implementation of CCS technology continues. Among the emerging legal issues associated with CCS technology are: 1. determinations of ownership and control of the underground pore space where the CO 2 would be "sequestered" under many of the CCS facility models proposed to date; 2. the question of which federal and state agencies would permit and regulate CO 2 pipelines transporting the gas from the point of emission to the sequestration site; and 3. concerns over liability exposure that may hinder development of CCS technology. Any entity wishing to operate an underground CCS facility must own or control the pore space in which the carbon dioxide would be sequestered or stored. However, since CCS technology has not yet been implemented and was not even considered until recently, most existing legal instruments related to property rights do not address ownership and control of pore space for purposes of sequestration or storage of carbon dioxide. Therefore, in order to determine who holds the relevant property rights, we must interpret the language found in such legal instruments and ascertain how it might apply to pore space to be used for CCS. In doing so, we can look to interpretations of courts that have reviewed similar or analogous property rights disputes. Traditionally, property law issues are handled at the state level. Indeed, most of the analogous disputes regarding subsurface "pore space" to date have been handled under state law, and presumably would be handled under state law going forward. These disputes, and subsequent actions by some state legislatures, have produced what is referred to in this report as the "majority rule" that holders of mineral rights do not, merely by virtue of these rights, have ownership or control of subsurface pore space. However, to the extent that CCS projects might take place on lands owned or controlled by the United States, determinations of pore space ownership and control also become an issue for the federal government. Because control of the pore space is vital to any CCS project, it is worthwhile to consider whether any private entity aside from the owner of surface rights might be able to claim ownership of, or control over, the relevant subsurface rights. The most obvious candidate would be the owner of "mineral rights" on/under the land in question, as mineral rights are, generally speaking, rights to something that is subsurface. In order to determine the potential legal hurdles facing CCS projects related to control of subsurface pore space, we must look at both state and federal common law and existing statutes and regulations. The majority of relevant case law suggests that a reviewing court would likely find that the pore space that would be used in CCS is not conveyed with mineral rights, but rather in most cases would remain with the holder of the surface rights. The majority of legal precedent suggests that the surface owner, not the holder of mineral rights, would have the relevant property interest in pore space for purposes of any CCS project. Indeed, most legal experts who have studied this issue have reached a similar conclusion. In the case of federal land on which the mineral rights are leased, this means that, although the holder of the mineral rights would have certain rights that must be considered in using the property, the federal government would have ownership of, and control over, the pore space that would be used for CCS. Experts have cited to a number of common law decisions in support of this conclusion. An instructive precedent to consider from federal court jurisprudence is Emeny v. United States. In Emeny , the United States Court of Claims was tasked with deciding whether the United States had acquired the right to store helium gas within a pore space formation on a certain property when the terms of the government's lease with the owner of the pore space were limited to the sole purpose of mining and operating for oil and gas. The plaintiffs in Emeny owned a tract of land in Texas which contained significant deposits of helium gas. The plaintiffs granted to a private gas company "oil and gas leases covering a total of approximately 217,000 acres of land, including the area which contains the Bush Dome." The United States eventually obtained these oil and gas leases from the private oil company, along with the remaining mineral rights that had been reserved by the plaintiffs, and compensated the respective parties accordingly. However, in the lease with the United States, the plaintiffs expressly reserved for themselves the surface of the leased lands, "including any such structure that might be suitable for the underground storage of 'foreign' or 'extraneous' gas produced elsewhere." Pursuant to the lease agreement, the United States commenced operations to extract the helium contained within the Bush Dome, and continued to do so for approximately three decades until the Bush Dome was empty. After the Bush Dome was emptied, the United States sought to store helium gas produced elsewhere inside of the now empty pore space. The plaintiffs argued that they were entitled to just compensation for the government's use of the Bush Dome as a helium storage facility because pursuant to the language of the lease agreement, the government only had a right to extract the gas contained within the pore space and no right to use the pore space for storage of helium gas produced elsewhere. After a consideration of Texas common law, the court in Emeny agreed with the plaintiffs that the government's property interest did not include the right to use the pore space for gas storage, and ordered the United States to pay the plaintiffs just compensation for its use of the Bush Dome as a helium storage facility. According to the court, "[t]here is no reasonable basis on which the rights granted to the [United States] in the ... oil and gas leases could be construed as including the right to bring to the premises and store there gas produced elsewhere." The West Virginia courts reached a similar conclusion in Tate v. United Fuel Gas Company . In Tate , the highest court in West Virginia addressed the question of pore space ownership once the minerals contained therein had been extracted. The owner of the land deeded the land to another man, but expressly reserved to himself the "oil, gas ... and all minerals ... underlying the surface of the land." The new owner then deeded the surface estate to Virgil Tate, subject to the same exceptions in the original deed, including the reservation of the mineral estate for the original owner. After extracting all of the oil from the pore space, the original owner eventually leased his remaining mineral rights to the defendant, United Fuel Gas Company. United Fuel Gas Company then used this mineral rights property interest to store gas produced elsewhere in the empty pore space. Plaintiff Tate, the owner of the land subject to the underground property interest leased to United Fuel Gas Company, asserted that the lease between the original owner and United Fuel Gas Company which gave United Fuel the "remaining" mineral rights was invalid, since the original owner/holder of the mineral rights only had a right to extract the contents of the subsurface estate, not the right to use the pore space for other purposes. The Supreme Court of West Virginia agreed with Tate and held that the express reservation of mineral rights only granted to the original owner/mineral rights holder (and his lessee, United Fuel Gas Company) a right to exploit the gas and minerals contained within the pore space, not a right to use the pore space itself for the storage of gas produced elsewhere. According to Tate , the owner of the mineral rights likely would not have the right to the use or lease the pore space for carbon dioxide capture and sequestration, unless the owner of the surface estate expressly allows the owner of mineral rights to use the pore space. This conforms with what is referred to here as the "majority rule" (and others have called the "American rule") that pore space is not conveyed with a standard conveyance of mineral rights. Another case that reached a similar conclusion is United States . v. 43.42 Acres of Land .