Oral or written evidence given by parties or their refusal to give evidence should be evaluated in the light of their special interest in the matter. Because of their special interest, the testimony of parties possibly should not be evaluated on the same level as that of neutral witnesses. This applies above all where parties have been present when witnesses have been heard and have ascertained the attitude of the competent department. The considerations set out in IV, 4.2 (Evaluation of the testimony of a witness) apply mutatis mutandis.