When it is considered by the Tribunal that there is sufficient evidence for a decision to be reached, the formal (and private) sessions of the Tribunal are held. The parties are not required to attend. The defender of the marriage bond is always present to uphold the ideals of the Church on marriage and its permanence. The decision will be made by judges of the Tribunal, and they will declare either that the marriage is certainly invalid or that the evidence does not prove invalidity with certainty and so the presumption that the marriage is valid remains.