See U.B.A. Plc vs. Mustapha (2004) 1 NWLR Part 855 page 443 where it was further stated that there is nothing in law which prevents a literate person from affixing his thumb impression to or on a document, and that the onus is on the person who object to a document to prove that the maker was an illiterate person. I think cognizance should be taken of the fact that due to the quest for being literate, some illiterate persons labour seriously to learn how to simply write their names at the end of a document to prove authenticity. The moment they learn how to write their names, that is sufficient for them.
– T.N. Orji-Abadua, JCA. Kabau v. Rilwanu (2013) – CA/K/179/2001