Comparative administrative law is an attractive and at the same time difficult research area. It fascinates, creates openness, gives a chance for the proper distance and perspective, as well as gaining theoretical and practical benefits. But also discourages researchers, deluding only such a possibility, driving into traps and dangers of various nature. Its value is determined by the usefulness of the results. The practical impact of scientific activity in the field of comparative law for comparative judicial reasoning can be described as: legitimacy, methodology and information.