[ULPIANUS libro primo ad Sabinum. ] §26.8.1.prQuamquam regula sit iuris ciuilis in rem suam auctorem tutorem fieri non posse, tamen potest tutor proprii sui debitoris hereditatem adeunti pupillo auctoritatem accommodare, quamuis per hoc debitor eius efficiatur: prima enim ratio auctoritatis ea est, ut heres fiat, per consequentias contingit, ut debitum subeat.
[ULPIANUS in the first book of his Commentary on Sabinus.] Although there is a rule of civil law that a guardian cannot become an authorizer on his own behalf, nevertheless a guardian can grant authority to a pupillus who is entering upon the inheritance of the guardian's own debtor, even though through this the pupillus becomes his debtor; for the primary purpose of the authority is that the pupillus may become the heir, and it happens only as a consequence that he undertakes the debt.
se tamen auctore ab eo stipulari non potest.
However, with himself authorizing, he cannot stipulate from the pupillus.
et cum quidam auctoritatem accomodaret pupillae suae, ut seruo suo stipulanti sponderet, diuus Pius Antoninus rescripsit iure pupillam non teneri, sed in quantum locupletior facta est, dandam actionem.
And when a certain person granted authority to his female pupillus to make a promise to his own slave who was stipulating, the divine Pius Antoninus wrote in a rescript that the female pupillus was not bound by law, but that an action should be granted to the extent that she was enriched.
sed si auctor fiat, ut filio suo quid tradatur, nulla erit auctoritas: euidenter enim sua auctoritate rem adquirit.
But if he should authorize that something be delivered to his own son, the authority will be null; for he clearly acquires the thing through his own authority.
§26.8.1.1Tutor si inuitus retentus sit per uim, non ualet quod agitur: neque enim praesentia corporis sufficit ad auctoritatem, ut si somno aut morbo comitiali occupatus tacuisset.
If a guardian is detained by force against his will, what is done is not valid; for the mere presence of his body does not suffice for authority, just as if he had remained silent while overcome by sleep or epilepsy.