[Amendment of the Kodeks rodzinny i opiekuńczy (Family and Guardianship Code), Chapter I. "Origin of a child"--some remarks of an expert witness in forensic genetics].

On June 13, 2009, the new Family and Guardianship Code came into effect. Many important modifications were implemented to Chapter I. "Origin of a child", the issue being of special importance in the work of a forensic geneticist. Those changes are related not only to arguableness of the fatherhood of both types--the one that is judged in lawsuit of denial of the fatherhood and that in which ineffectiveness of paternity is recognized--but for the first time they also demand on maternity testing. The Code defines who--according to Polish law--is a mother to a child and on this base states motherhood. In consequence, the main legal maxim Mater semper certa est, which has existed since Ancient Rome times is now annulled. The paper presents some remarks of an expert witness on the introduced changes.