Introduction:
Insanity is an issue at the border between two different fields of science: law and medicine. Medicine is a widely developed field that undergoes continuous and dynamic development. On the other hand, legal aspects of medicine are based on classical medical solutions adopted already in the 19th century science. Insanity is a strictly legal term. Definition of this term is an extremely important aspect for the application of Art. 31 of the Penal Code, since its interpretation determines criminal liability, and in consequence the use of criminal penalties or security measures.

Aim:
The aim of this work was to present the issue of insanity in respect to the Polish Criminal Law and current medical knowledge.

Material and methods:
Dogmatic-legal analysis of the current legal regulations in Poland through the prism of well-established Supreme Court jurisprudence and literature of the field was conducted.

Results and discussion:
Recently, the condition for liability of a perpetrator for a criminal act is guilt, which in certain circumstances may be excluded. Culpability does not occur inter alia in situations where the state of mind of the perpetrator shows some deficiency. A Polish legislator provides three sources of insanity: mental illness, mental retardation, and other mental disturbance activities. Two psychological criteria of the very state are also defined, which at the same time are the consequences of the above-mentioned sources: inability to recognize the significance of the act and inability to manage its conduct.

Conclusions:
The issue of insanity requires effective combination of complex and suitable legal structures, current medical knowledge, and interest of an individual and society. For the effective and accurate regulations of the issue of insanity and well-functioning practice, a dialog between the two professions is required. Specifying the term of insanity is the responsibility of physicians, since its clarification on the basis of current legal status is unreasonable and inadequate due to the fact that its extent is each time determined by the current medical knowledge.