I wonder what a diagram of incentives and responsibilities of a contemporary police force would look like. In terms of responsibilities, there is actual enforc

I wonder what a diagram of incentives and responsibilities of a contemporary police force would look like. In terms of responsibilities, there is actual enforcement of the law, and there is investigating crimes (there maybe more responsibilities too). A lie-detector would be a part of the "investigating crimes" section. One could argue that it is a "labor-saving device", but a similar argument can be made for it being an "evidence-creation" device. However, both characterizations yield a common concern: the outcome. What are the outcomes of a criminal investigation? For each outcome, what are the costs and who pays each cost? Is that cost the desired cost given the outcome? True positive True negative False positive False negative Given we are talking about crimes, there may be more than one way to get to each of the four outcomes above.