Okla. Stat. tit. 12, § 12-1181: Mutual defense by garnishee and defendant

At any time before final order or judgment against the

garnishee, the defendant may in all cases, by answer duly verified

defend the proceedings against any garnishee, upon the ground that

the indebtedness of the garnishee, or any property held by him, is

exempt from execution against such defendant, or for any other

reason is not liable to garnishment; or upon any ground upon which a

garnishee might defend the same; and may participate in the trial of

any issue between the plaintiff and garnishee for the protection of

his interests. The garnishee may at his option, defend the

principal action for the defendant, if the latter does not, but

shall be under no obligations so to do.