This chapter focuses on the Pareto Type I clutter scenario. It reviews the development and generalisation of switching detectors, while the latter two shows how a switching constant false alarm rate (CFAR) detector can be constructed from. It explores the developments of switching-based detectors based upon that in Weinberg, with the focuses on the GM-detector. The reader will observe that numerical analysis of the switching-based detectors has not yet been included. Due to numerical complexity it is somewhat simpler to use receiver operating characteristic (ROC) curves to examine the performance. These plot the Pd as a function of the Pfa, where the target model in the cell under test (CUT) has fixed signal to clutter ratio (SCR). Since switching detectors compare the clutter range profile (CRP) to measurements of the CUT it is faster to produce ROC curves.