As currently authorized in the Adam Walsh Act and as noted in our interim report, the registry could not include sufficient identifying information to accurately identify perpetrators. Under current law, the registry could contain only the perpetrator's name and the nature of the maltreatment substantiated. Our research has determined that such limited information would result in an extremely high rate of inaccurate (i.e. false positive) matches, rendering any results of inquiries to a national registry worthless.
In our research we tested how frequently persons identified as child abuse perpetrators in 2009 had matching records in another state's perpetrator records for the five-year period of 2005-2009. These hypothetical queries resulted in a match 89 percent of the time when only name (last name and first initial) was used to identify the individual. However, if the perpetrator's sex and birth date were also included as matching criteria (not permitted under current law), the match rate dropped to 1.5 percent (or an estimated 7,852 individuals nationally). We believe the 1.5 percent figure is the best possible estimate of the number of perpetrators who appear in multiple states' registries. It is essential that the perpetrator's date of birth (and preferably sex as well) be included in a national registry in order to be reasonably confident that the same individual is involved in both cases. Even then, there would undoubtedly be some false positive matches, though our research could not determine how many.
Because most persons listed in state child abuse registries are parents of the victim(s), in our research we considered whether including victims' dates of birth as additional identifying criteria would produce better matches. However, we found that requiring those matches include date of birth for at least one child on the record further reduced the number of matches by nearly 75 percent. Because fewer than half the states include in their perpetrator databases the birth dates of all children in the household, we concluded that including such a match criterion had more potential to produce false negative results than it did to improve true positive matches.
Even if matches are made based on name, sex, and birth date of the perpetrator, there will be cases in which the individual about whom the inquiry is made asserts they are not the same person as is identified in the registry. Resolution of such cases would necessitate contacting the originating jurisdiction to try and sort out what additional identifying information in the case file (e.g. names and ages of perpetrators' children) might determine whether the match is a true positive or a false positive. While possibly manageable in the case of investigative inquiries, if the registry is used also for employment inquiries the issue of false positives becomes more time consuming to resolve on a case-by-case basis. In states that permit their registries to be used for employment inquiries, those inquiries vastly outnumber investigative inquiries (typically by a ratio of four or five to one). In addition, we expect state child protective services agencies to be less willing to spend staff time resolving such disputed matches when the inquiry does not pertain to a pending investigation.