Borys Łapicki (1889–1974) was a Roman law scholar whose works contained many references to the correlations between Roman law and ethics. The article provides an overview of B. Łapicki’s writings and discusses his views on the concept of misericordia and on the influence of that concept on Emperor Justinian’s criminal legislation. A definite and clear-cut thesis emerges from this analysis. Borys Łapicki declares that although Justinian was an emperor who considered himself and was considered to be the great defender of the Christian faith, his legislation was influenced by the principle of utilitas rei publicae, rather than by Christian misericordia and by the humanitarian principles of the New Testament ethics. This is particularly evident in his criminal legislation. This leads B. Łapicki to conclude that it was “not Christianity that influenced Justinian, but on the contrary, he exercised his influence on Christianity so that it could serve his political purposes.”