The question of proof in the proceedings for the declaration of nullity of marriage is quite extensive and multidimensional at the same time. We should keep in mind that the process permits evidence that is not mentioned in the 1983 Code of Canon Law, but which arises due to the progress of modern technologies and observed increase of public involvement in the ‘virtual world’. Therefore, in the future, one should expect only an upward trend in this matter. However, not only the evolving catalogue of proofs affects the extent of the issue. We should also look at the probative value of each of them, as well as their assessment by the judge. These elements are relevant from the procedural point of view, because thanks to the disclosure of the probative and free force and a reasonable assessment of evidence, the judge will obtain, or not, moral certainty that will enable him to resolve the case and pass a sentence. Therefore, it seems necessary to study the issue of proof while keeping a certain balance and maintaining focus on its probative value and assessment by the judge in trial.