The recognition of the Polish-Lithuanian Commonwealth in the 16th and 17th centuries is probably questionable. This country is assessed mainly through negative judgments based on stereotypes. In fact, in the Polish-Lithuanian Commonwealth there was a development of democratic forms typical of a constitutional state, which certainly differed from solutions in other states in Europe, which at that time were mostly subject to absolute rule. The aim of the work is to present the development of democracy in the Republic of Poland, show the conditions of this development, and, above all, demonstrate that this development was based on constitutional norms and principles adopted in the law-making process and generally applicable.