Comparer to the burgeoning literature on the determinants of penal policies in various western countries, and compared to criminology in general, the comparative study of policing is an underdeveloped area of research. We acknowledge the pratical and theoretical difficulties of such a approach, but we defend its main benefits. Studying policing comparatively allows for a better knowledge of national systems, an understanding of basic concepts such a centralisation, and a stronger recognition of the diverging and converging trends in policies at a global level. Traditional comparisons of national models considered policing systems in broad categories (anglo-saxon versus continental european, for example). Here, we suggest rather that models need to be broken down into their elementary components and main organisational features (degree of centralisation, mechanisms of oversight and others).