Abstract
This paper aims to answer the following research problem: what are the models of reasonable (proper) implementation of public expenditure arising from specific constitutional rules, and what are the standards for such spending? The authors present a thesis that the constitutional principle of legality, as well as the principle of public finance as a good which is protected constitutionally, sets general models, which consequently determine the standards of reasonable (proper) spending of public funds in the broad sense, i.e. in the context of legality and economy (purpose, economy, effectiveness and efficiency). Notably, these models and standards meet the postulate of complete financial control, i.e. at every stage of the budget procedure (budget design, planning and execution). The article uses so-called non-reactive research methods, based on the analysis of the content and availability of source information, i.e. theoretical and legal publications as well as legal regulations (especially constitutional ones) crucial from the point of view of the selected subject.