This paper is devoted to the participation of senators in Arian controversy of the 4th century. The author analyzes two historical situations: the dispute of Photinus of Sirmium with Basil of Ancyra at the council of Sirmium (351), in which members of the Senate of Constantinople took part as arbiters, and the demand of Palladius of Ratiaria after his conviction at the council of Aquileia in 381 to bring his dispute with St. Ambrose to judgment of the Roman Senate. This model of resolving church conflicts is based on the idea that doctrinal truth can be proved by logical arguments in a theological dispute. Members of the Senate ideally suited the role of authoritative but neutral observers. However, the practice of participation of the Senate in theological debates did develop further during the Arian controversy. Theological traditionalism triumphed over rationalism and supreme doctrinal authority remained the prerogative of bishops.