It is also a problem when the DNA isn’t obvious that it is connected to the perpetrator of the crime. Semen found inside a victim is very different than DNA found inside a room where a crime occurred, which is different than DNA found at a crime scene in a public or semi-public place. If you can just collect up a bunch of DNA and run it against everyone, with no initial justification of probable cause, you can get innocent people that are guilty of no more than leaving their DNA somewhere and not having an alibi being victims themselves of lazy police investigations.
