In other words, it is public policy to encourage citizens to inform on one another. The problem is the reliability of their testimony. While the use of informers spans the course of human history, and we will always be saddled with it, we should not have to hold our nose every time a snitch takes the stand to swear the truth. On the practical side of informer testimony, few inroads into the containment of organized crime and modern terrorism would be possible without the little guy ratting on the big guys. These criminal elements, in many ways, are more powerful than the government and very adroit at dodging the law.
Informers are absolutely necessary to level the playing field.
Mandatory minimum sentences and draconian federal sentencing guidelines leave the poor devil little choice but to tell the prosecutors what they want to hear. It's bribery, and the safeguards against its inherent unreliability are inadequate. So much for getting government off our backs. So, bought testimony that is intertwined with plausible half-truths and the extreme incentive to curry favor with the prosecution does not tear at the bloodless hearts of this court. The oldest human rights principle in Anglo-American legal heritage is that the king is subject to the law.