A scientist examining some aspect of nature has a range of optical implements at her disposal, such as a microscope, a magnifying glass, and a telescope. The view she obtains and the conclusions she reaches are in part a function of the instrument she selects. An appellate court is in a similar situation, but instead of having a choice, the tool it must use is determined by the type of issue it is considering. The lens through which an appellate court assesses the ruling