The proposal for assessment of expert testimony in a holistic trend procedural system  is a study from the epistemology of testimony about the justification of acceptance of knowledge in the decision. It is concluded that the assessment should not be limited to  a judge’s soliloquy with its reduced knowledge of life, but rather he requires a previous experiment in the procedural context in which expert evidence is subject to admissibility test, the interrogations in their practice and other activities to help the judge to establish signs of relibly about the expert witness and his knowledge.