ABSTRACT

Using the re-identification metrics and decision rules outlined previously requires that certain thresholds are set. In this chapter we will provide some guidance on setting thresholds for identity disclosure decision rules. Privacy statutes and regulations do not provide an explicit definition of what is an acceptable risk of reidentification. As noted earlier, many statutes use a reasonableness standard. For example, Ontario’s PHIPA states that “identifying information means information that identifies an individual or for which it is reasonably foreseeable in the circumstances that it could be utilized, either alone or with other information, to identify an individual,” and the U.S. HIPAA describes de-identified information where “there is no reasonable basis to believe that the information can be used to identify an individual.” We can turn to precedents as a basis for deciding on acceptable risk levels for our three thresholds.