Dear Ignalo:

Canon Law states:

924 ß1 The most holy Sacrifice of the Eucharist must be celebrated in bread, and in wine to which a small quantity of water is to be added.

ß2 The bread must be wheaten only, and recently made, so that there is no danger of corruption.

ß3 The wine must be natural, made from grapes of the vine, and not corrupt.

926 In the eucharistic celebration, in accordance with the ancient tradition of the Latin Church, the priest is to use unleavened bread wherever he celebrates Mass.

I can only answer this to the degree that I understand it, as I have not found any definitive answer.

Your question speak to the licitness of certain circumstances dispensing from the requirements of Canon Law.

I can only speak according to my understanding of general principles since I could not find any statement from an authoritative source.

Certainly, departing from the requirements of Canon Law can be dispensed, I think, by a Bishop for just and extraordinary circumstances and grave reasons. Outside of a bishop's dispensation I would think must be extremely limited to very extraordinary grave circumstances where access to the Bishop is not possible. There are very few circumstances when this would occur.

A priest in prison, under normal circumstances, will not be saying Mass, unless he says Mass in the Prison chapel, which will have the proper elements for the Eucharist.

A priest in a secluded place also cannot say Mass unless he brought unconsecrated hosts with him on his trip to the secluded place for vacation.

The only circumstances I can think of that may qualify for an exception to Canon Law or a Bishop's dispensation would be, for example, a priest in the concentration camps of Nazi Germany. Maybe priest in prison for their faith, such as in China and other repressive countries.

A priest lost in the forest or desert on a long-term basis with little hope of rescue, or shipwrecked on an isolated uninhabited island may be an exception also.

These sorts of extreme situations "may" offer an acceptable exception. In other more normal situations, such as a priest in a normal prison or a priest in a secluded area, would either have to just not say Mass or have the Bishop's dispensation if the proper elements for the Eucharist are not available.

Perhaps one of our readers will have something more certain about this.

God Bless,
Bro. Ignatius Mary