Oklahoma constitution
Article V: legislative power
Section 57

Every act of the Legislature shall embrace but one subject, which shall be clearly expressed in its title, except general appropriation bills, general revenue bills, and bills adopting a code, digest, or revision of statutes; and no law shall be revived, amended, or the provisions thereof extended or conferred, by reference to its title only; but so much thereof as is revived, amended, extended, or conferred shall be re-enacted and published at length: Provided, That if any subject be embraced in any act contrary to the provisions of this section, such act shall be void only as to so much of the law as may not be expressed in the title thereof.