Okla. Stat. tit. 12A, § 3-407
Oklahoma Code Comment
1. This Section makes no substantial change to Oklahoma law, although the 1992 revisions clarified this Section somewhat. Where Oklahoma cases under pre-revision Section 3-407 focused on whether an alteration was "material," post-revision cases will likely focus on whether there was an "alteration" at all, and then whether the alteration was "unauthorized" or "fraudulent." As under the pre-revision Section, a fraudulent alteration discharges a party whose obligation is affected by the alteration. See e.g. Inter-City Fin. Corp. v. Hooker, 168 Okla. 10, 32 P.2d 277 (1934) (materially altered note unenforceable by payee against non-consenting co maker), Campbell v. Vance, 118 Okla. 283, 248 P. 634 (1926) (material alteration of instrument by holder extinguished liability of non-consenting makers); German-American Bank v. Hennis, 54 Okla. 146, 153 P. 671 (1915) (payee erased one maker's name without consent of co-makers and then assigned note for value; note was void and assignee could not enforce against non-consenting co-makers). However, even a material alteration may be ratified or waived, making the instrument enforceable as to its altered terms. See, e.g., Swartz v. Bank of Haileyville, 169 Okla. 22, 35 P.2d 701 (1934); Campbell v. Vance, 118 Okla. 283, 248 P. 634 (1926).
2. Subsection (b) provides that only fraudulent alterations will effect a discharge. Thus, for example, if an instrument is mistakenly altered, even though the alteration is unauthorized, the instrument may still be enforced according to its original terms.