Two versions of the saga of Fergus mac Léti are found in legal material associated with the Senchas Már; one in the original text, and one in the eighth-century commentary. The commentary version and §2 of the older version have both been edited by D. A. Binchy. It is argued here that §1 of the older version and §2 of the commentary version are both in verse. The older version is then analysed in terms of the law of distraint. It is concluded that the saga was written as a legal teaching tale, with its plot-twists deliberately designed to highlight aspects of the law. An appendix argues for the inclusion of an additional section, omitted by Binchy, in the commentary version of the saga.