The law on communication in sacris is merely an ecclesiastical law. It is one of the positive fruits of the Church’s commitment to ecumenism as manifested in the two decrees of Vatican II Council: Orientalium Ecclesiarum and Unitatis Redintegratio. This law permits Catholics and baptised non-Catholics to share the sacraments of the Eucharist, penance, and anointing of the sick in exceptional cases of spiritual need, and also sharing in other forms of non-sacramental liturgical worship.   

The book elaborates the conditions that must be fulfilled by the Catholics before they ask for these three sacraments from a non-Catholic minister, and the conditions to be fulfilled by the baptised non-Catholics before they can request for these sacraments from a Catholic minister.

 The book also explores other forms of permitted sharing in non-sacramental liturgical worship handling major questions of concern, like imparting blessings upon non-Catholics by Catholic ministers and many others. It culminates with the presentation of various particular laws enacted by the episcopal conferences and diocesan Bishops on this matter all over the world.