Estimating the subject's ability to undergo imprisonment and determining whether there are any reasons for delaying or stopping imprisonment, has become a serious problem. Currently the Polish system lacks clear and homogenous opinionating criteria, and the available sources provide only general guidelines. This results in a great deal of discrepancy between opinions and evaluations made in similar cases. This work attempts to define and illustrate the criteria of the Executive Penal Code that are used in evaluating whether imprisonment is to be delayed or stopped. The authors have also provided examples of illnesses that would illustrate those definitions/criteria and came up with a suggested procedure of decision-making to be applied to such cases.