1866 Instruction of the Holy Office in Response to questions form the Vicar Apostolic of the Galla tribe in Etheopia

... slavery itself, considered as such in its essential nature, is not at all contrary to the natural and divine law, and there can be several just titles of slavery and these are referred to by approved theologians and commentators of the sacred canons.

For the sort of ownership which a slave- owner has over a slave is understood as nothing other than the perpetual right of disposing of the work of a slave for one's own benefit - services which it is right for one human being to provide for another.

From this it follows that it is not contrary to the natural and divine law for a slave to be sold, bought, exchanged or donated, provided that in this sale, purchase, exchange or gift, the due conditions are strictly observed which the approved authors likewise describe and explain.

Among these conditions the most important ones are that the purchaser should carefully examine whether the slave who is put up for sale has been justly or unjustly deprived of his liberty, and that the vendor should do nothing which might endanger the life, virtue or Catholic faith of the slave who is to be transferred to another's possession.

In answer to a question from the Vicar Apostolic the Holy Office replied that Christians may lawfully acquire slaves by purchase or gift provided that they have been justly enslaved.

If they have been unjustly enslaved but nevertheless refuse to be sold or given to Christians, they may not be purchased or accepted, for their freewill must be respected.

If they have been unjustly enslaved and freely offer themselves to be the slaves of Christian masters under a milder form of slavery as the only means of escaping from their present harsh form of slavery, and as a means of coming to know about Christian worship, they may be acquired and held as slaves by Christians by just title (e.g. purchase), provided that they are treated with Christian charity and instructed in the rudiments of the faith with a view to their conversion to Christianity by their own free choice.