Originally Posted by Mleake
arentol, while the situation in particular was not the same, the issue was the permissibility of defense expert witnesses being allowed (or not) to testify about the GSR results from tests of Bias's handloads.
How could this come up in a self-defense scenario? Let's say we have a he-said / he-said shooting. The shooter claims self-defense, and says the aggressor was charging him with a knife. He shot when the guy was very close; the shootee says, no, I was nowhere near that close, and I was not attacking him.
GSR shows less than expected for the range the shooter claims.
Prosecution witness says the GSR indicates that the shootee's story is the correct one.
Defense witness can't testify that the shooter's handloads burn cleaner, and produce less GSR, because rules of evidence won't allow testing of evidence that was manufactured by the defendant. Even though the witness might run multiple tests that show the defendant's loads produce that low GSR result at the range the defendant claims, the judge might never allow that into evidence.
Putting aside that the defense WAS allowed to testify about the handloads, making your entire argument invalid, even that is unnecessary because your example defeats itself....
If the defense can not test the handloads then the prosecution can not either. Can't have that both ways. If neither side can test them then neither can make any testimony regarding the GSR except entirely factual ones like: No GSR was found, or 10 particles were found, or 100 per square inch were found. That is all they can do, and no distance can be claimed from any of that information because they can not test the ammo to provide the evidence they need to make such a claim. So nobody can claim that less was found than expected for the range the shooter claims. At that point the GSR only helps the prosecution if there is none found, and the GSR only helps the defendant if so much is found that the shooting had to be within a few inches. Anything else and there is just too little information to say who is telling the truth.
The main lesson learned from the example is that if you are going to handload for defense keep logs of what you make and when you make it, and keep clearly marked extras that were made alongside and the same as your defensive loads for as long as you carry those defensive loads so you have potential exemplar evidence if you need it.