Okla. Stat. tit. 12, § 2705
The expert may testify in terms of opinion or inference and give his reasons therefor without prior disclosure of the underlying facts or data, unless the court requires otherwise. The expert may be required to disclose the underlying facts or data on cross-examination.
Laws 1978, SB 276, c. 285, § 705, eff. October 1, 1978.