Forensic practice is more and more under scrutiny, both from the general public and the scientific community. Press reports about forensic examination in criminal cases regularly question the scientific foundation of forensic science and challenge the results of its analysis and interpretation. The forensic community is currently actively developing and implementing quality assurance by establishing worldwide harmonized minimum quality standards. In forensic evidence evaluation practitioners assign a strength of evidence to forensic observations and analytical results, in order to address hypotheses at source or activity level. The validation of the theoretical aspects rests upon mathematical proof or falsification. The validation of the empirical aspects rests upon the acceptance or rejection of validation criteria on the basis of experimental results. The assessment of the goodness of probabilistic opinions has been the focus of extensive research in statistics since long.