I can go down to the government archive and as a citizen request to view blueprints of buildings. I may not copy the design to build my own building, nor use patented aspects, but I am allowed to inspect or ask a independent expert to review the design and find flaws. Unsurprisingly this has not killed the architect profession, nor forced construction companies to open source their technologies.
This is sufficient for most cases because the likelihood of that evidence being "wrong" when you combine it with other factors like motive, eye-witness accounts and other non-physical evidence is very slim.
On the body part it's a bit more complicated it's more a CSI effect people think that all cases have tons of physical evidence and that everything is cool and flashy and high-techy in reality most cases have very little physical evidence and labs might not be used at all most bodies are inspected at by the county coroner's office which might be quite inadequate of collecting that sort of evidence we come to expect by watching crime procedurals.
I sat on a jury a couple years back and the prosecutor's opening statement addressed this issue in the first seconds of the case. He worked hard to make a distinction between reality and television. This was a smart move, as some of the people on that jury turned out to be dumb as rocks when we went into deliberation. I'm sure this is true of most juries.