The paper deals with the sale on
approval of horses and mules shown in D.19,5,20 pr.- 1 (Ulpianus libro 32 ad edictum) and the existing theories on
the legal position of the parties in the source. The first part of the paper
sets out principium of D.19,5,20, where Ulpian quotes Labeo, and his
description of the sale on approval of horses, concluded between the seller and
the acrobatic rider – desultor, with a detailed analysis of the interpretations
of relevant romanists. The principium is analyzed with the reference to dominant theories: theses on the suspensive and/or resolutive
condition pactum displicentiae, on the innominate contract, and on
pre-contractual acts. This is followed by an analysis of Ulpian’s sequel in the
first paragraph of D.19,5,20 with a quotation of Mela, where he describes the
sale on approval of mules, which are stolen during the test period, with Ulpian’s quote of Mela’s dilemma and of comparison
with his own. Next part of the paper contains theories and interpretations of
the legal nature of the relationship between the parties and the stage of
contract. In conclusion, author presents his own position on the both presented
situations, the legal nature of the relationship between the parties, and finally on the legal problem raised
by Ulpian in the cited sources.