Comment Re: Get a warrant (Score 3, Insightful) 43
According to your logic, a warrant would be required before they knock on the eyewitness's door and ask if he's seen anything suspicious.
No one but you has said or implied anything of the sort.
You're free to knock on anyone's door and ask them questions, no warrant required. They are free to refuse to open the door, to not answer your questions, to slam the door in your face, or to order you to get off their property. Same for police.
If you want to compel someone to provide a DNA sample so you can match it against one from a crime scene, that definitely requires a warrant.
So you say, "That's too much trouble. I'll just go to a private company that has already collected DNA on millions of people. Those millions of people didn't agree to have their DNA used for criminal investigations, and all their relatives who share DNA with them didn't agree to have it used for anything at all. But who cares? I'll just pretend it doesn't need a warrant."