Many rapists, because of this, now plead guilty. In essence, DNA evidence is rapidly becoming, in principle, an irrefutable proof of identification. But of course, nothing is ever so simple. Scientists are a demanding lot, a skeptical lot, a rigorous lot. And although everyone agrees that this is a spectacular technology, controversies have erupted in the scientific community from time to time over whether it's really being done right.
Fights erupt over DNA fingerprinting because it's such an important technology.
They have not been about how to do it in principle. They have been about how to do it in practice, and how well-regulated the practice is. For example, DNA fingerprints should look like bar codes. It's one I know well, because it was one where I was asked to serve as an expert witness, which is how, from my medical genetics background, I got deeply involved in this. It was an interesting case, because it showed what scientists can do when they put their heads together.