As in other legal systems certain factors can vitiate the quality of consent and thus make the agreement void or voidable. These are – (a) mistake, (b) misrepresentation (fraudulent or non fraudulent), and (c) undue influence and coercion. In principle, the law of Sri Lanka also takes of provision for these factors. As to mistake, an erroneous impression, it may (i) prevent agreement, or (ii) nullify the agreement. Though, in Sri Lanka the system of law operative is the Roman Dutch law, yet English cases seem to be often cited in this field. Moreover, the Evidence Ordinance of Sri Lanka closely follows the Indian Evidence Act, 1872, so that, in the light of section 92 of that Ordinance (and its various provisos) evidence is freely admitted of factors nullifying a transaction for want of consent.