Okla. Stat. tit. 12A § 2-202
Terms with respect to which the confirmatory memoranda of the parties agree or which are otherwise set forth in a writing intended by the parties as a final expression of their agreement with respect to such terms as are included therein may not be contradicted by evidence of any prior agreement or of a contemporaneous oral agreement but may be explained or supplemented:
Okla. Stat. tit. 12A, § 2-202
Oklahoma Code Comment
Oklahoma law is changed by this section.
The Oklahoma parol evidence rule, 16 O.S. § 137 reads: "The execution of a contract in writing, whether the law requires it to be written or not, supersedes all the oral negotiations or stipulations concerning its matter, which preceded or accompanied the execution of the instrument." Comparing this language to the Commercial Code, we find these differences:
Previous Oklahoma decisions held it was presumed that the written contract was intended to include all the terms of the agreement. Warren v. Pulley, 183 Okl. 88, 141 P.2d 288 (1943). There is no such presumption under the Commercial Code
Previous Oklahoma decisions held that evidence of custom, usage, course of dealing, or evidence of consistent additional terms could be introduced only:
When the language of the contract is ambiguous, Manley v. Boling, 186 Okl. 59, 96 P.2d 30, (1939), Rence v. Blubaugh, Okl., 285 P.2d 414 (1955), or
When the written contract does not purport to include all the terms of the agreement, Wat Henry Pontiac Co. v. Bradley, 202 Okl. 82, 210 P.2d 348 (1949).
The second purpose of this section stated in the Comments is similar to the provisions of 15 O.S. §§ 160, 161.