National DNA databanks were initially established to catalogue the identities of violent criminals and sex offenders. However, since the mid-1990s, forensic DNA databanks have in some cases expanded to include people merely arrested, regardless of whether they've been charged or convicted of a crime. The public is largely unaware of these changes and the advances that biotechnology and forensic DNA science have made possible. Yet many citizens are beginning to realize that the unfettered collection of DNA profiles might compromise our basic freedoms and rights.

Two leading authors on...