Canon 1116

Can. 1116 §1. If a person competent to assist according to the norm of law cannot be present or approached without grave inconvenience, those who intend to enter into a true marriage can contract it validly and licitly before witnesses only:
1º in danger of death;
2º outside the danger of death provided that it is prudently foreseen that the situation will continue for a month.

Can. 1116 §2. In either case, if some other priest or deacon who can be present is available, he must be called and be present at the celebration of the marriage together with the witnesses, without prejudice to the validity of the marriage before witnesses only.

Can. 1116 §3. In the circumstances mentioned in §1, nn. 1 and 2, the local ordinary can confer on any Catholic priest the faculty of blessing the marriage of the Christian faithful of Eastern Churches which do not have full communion with the Catholic Church, if they spontaneously seek it, and provided that nothing prevents the valid and licit celebration of the marriage. The priest himself, if it can be done prudently, is to inform the competent authority of the non-Catholic Church concerned.