It is trite law that mere thumb-impression on a document tantamount to prima facie as in this instant case, is prima facie evidence that the person who appended his thumb-impression is/was an illiterate. In this case, the appellant has the burden to readily prove to the satisfaction of the court that he is an illiterate.
– Sanusi, JSC. Umaru Sunday v. FRN (2018) – SC.145/2013