Very true. There have been numerous criminal cases that have been thrown out based on invasion of the body. I remember one where a doctor provided a blood sample to the police of a drunk driver. We can say that this is all noble and getting a drunk driver off the road, but consider the implications of allowing this type of evidence: it means that a doctor can use a part of your body to incriminate you by obtaining that part for another purpose. The charges were dropped for that very reason.

What I am saying is simply this: when it comes to your own body, you should have the final say on how parts of your body are to be used. No one should be compelled to give a sample for the "greater good", and laws should not be redrafted to allow this kind of invasion.