The USSC ruled cops can take a DNA sample IF you’re suspected of a serious crime, but not otherwise.
http://www.nytimes.com/2013/06/04/us/supreme-court-says-police-can-take-dna-samples.html
The Supreme Court ruling on DNA samples concerned a lawsuit that was brought regarding a case in Maryland.
Legal experts, at least some of them, said the Supreme Court ruling was specific to that Maryland case.
If more widespread DNA samples are taken from “suspects” beyond the parameters of the Maryland case, these same legal experts believe the Supreme Court will have to re-visit the issue of DNA samples.
Personally, I was appalled at that Supreme Court ruling. DNA samples should only be taken from criminals who are convicted of certain felonies, such as murder, attempted murder, child kidnapping, rape, etc.