CODIS currently contains more than four million DNA profiles from convicted offenders and more than 160,000 DNA profiles obtained from crime scene evidence. All 50 states participate in CODIS, although the laws authorizing DNA collection, analysis, and entry into databases vary considerably. Every state takes DNA samples from convicted sex offenders, more than 40 states allow collection of samples from all convicted felons, at least 38 allow from convicts of certain qualifying misdemeanors, eleven allow from those arrested for certain crimes, and one state permits collection from individuals detained as suspects. The passage of the DNA Fingerprinting Act of 2005 allowed CODIS to include samples from any individual from whom collection was authorized under state law, and also permitted inclusion of DNA from federal arrestees and from non-U.S. detainees. These changes in the law have led to a dramatic expansion of forensic DNA databases.
http://www.dnapolicy.org/images/issuebriefpdfs/DNA, Forensics, and the Law Issue Brief.pdf