Okla. Stat. tit. 74 § 456.2
In addition to those joint committees provided by law, the President Pro Tempore of the Senate and the Speaker of the House of Representatives shall be authorized to establish joint committees of the Legislature as they deem necessary. Said joint committees shall be composed of members from the Senate to be appointed by the President Pro Tempore of the Senate, and members from the House to be appointed by the Speaker of the House of Representatives. Joint committees and subcommittees of joint committees shall be authorized to meet when the Legislature is not in session, subject to such restrictions as may be imposed by the President Pro Tempore of the Senate and the Speaker of the House of Representatives. Members of the Legislature and the officers thereof shall be reimbursed their expenses in attending meetings of joint committees and subcommittees of joint committees of which they are members or to which they are invited by committee chairmen when the Legislature is not in session.
Okla. Stat. tit. 74, § 456.2