There is general agreement that geologic disposal of long-lived radioactive waste provides the greatest degree of isolation from the biosphere, and hence the greatest protection for humans, over the extended time frames during which the waste presents a hazard. Geologic disposal has an additional advantage in that it does not rely on active institutional controls to maintain and protect the facility, but is instead intended to operate passively even if all knowledge of the facility is lost. Thus, geologic disposal does not rely on the questionable assumption that governmental or other responsible institutions can be maintained in perpetuity; this, however, also raises the possibility that some future human action could be taken that disrupts the repository and compromises its ability to isolate the radioactive material. It is clear, therefore, that some evaluation of this possibility must be included in the overall safety case for the facility. The nature and extent of the analysis, as well as the relative importance it is assigned within the safety case, is less clear.