Okla. Stat. tit. 12, § 12-718.6: Procedure for recognition of foreign-country judgment

A. If recognition of a foreign-country judgment is sought as an

original matter, the issue of recognition shall be raised by filing

an action seeking recognition of the foreign-country judgment.

B. If recognition of a foreign-country judgment is sought in a

pending action, the issue of recognition may be raised by

counterclaim, cross-claim, or affirmative defense.