The legal proceedings that Andrasta outlined were first written down in the 5th to 8th centuries and survived in 14th to 16th century manuscripts.

There is a great deal of variation in the degree of Christian influence in the law texts. The Cáin Lánamna gives detailed descriptions of the procedure for divorce without any word of condemnation. However the author of Heptad 51 quotes from St. Mark 10:9. The author of Bretha Crólige frankly admits that there is dispute in the law as to whether or not its allowable to have many sexual unions or a single one.

It is still possible though to peel back the layers and the subsequent glosses and get a very good glimpse of Celtic law as it existed before Christianity.

The Seanchas Mór, that wonderful Irish collection of laws, does not represent a codification of the law but more digests or compilations of generations of learned Brehons. We can also compare the Brehon Laws with those of the Hywel Dda and see a remarkable resemblance.