Okla. Stat. tit. 12 § 2003 : — Civil ProcedureOklahoma Pleading Code — Commencement of Action TEXT PDF A civil action is commenced by filing a petition with the court. Okla. Stat. tit. 12, § 2003 Added by Laws 1984, SB 417, c. 164, § 3, eff. 11/1/1984.