Actually, Rose Red, when using scientific evidence in trials -- any trial, judge alone or jury trial, the one offering the evidence has to lay a foundation first by asking questions designed to show that the evidence is reliable and done according to accepted scientific methods so the same result will happen time and time again under the same circumstances AND that it is accepted to prove the fact that is sought to be proved, by the scientific community. For dog evidence, a lot of evidence comes in showing the training of the dog, the credentials of the trainers, the credentials of the dog handlers, the number of times the dog was used, results, etc. Lots of foundation goes into this and it chews up a lot of court time to present it. Further, the defense may object on many grounds. One common ground is an objection that the evidence is too prejudicial and the prejudice outweighs the probative value of the evidence. Sometimes a judge will sustain an objection based on that ground. Then again, sometimes judges just make rulings on motions that are wrong and the prosecution can preserve the objection and take it up on appeal. However, if the prosecution wins the case based on other evidence, obviously they don't appeal. I just thought you deserved a better explanation than just argument on this one. It was a good point.