The single-subject rule is a part of the Oklahoma Constitution that requires individual ballot initiatives and legislation may deal with only one main issue. The single-subject rule is found in over 40 state constitutions as a way to prevent “log-rolling”, the legislative practice of combining several distinct matters in one bill, even when some of them may have passed the legislature by themselves.
The Oklahoma Constitution states, “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….;” (Article V, Section 57).
The Oklahoma Supreme Court has invalidated numerous laws as violations of the single-subject rule, including appropriations bills that provide funding for more than one agency, abortion legislation, and most recently (2013) tort reform legislation and a bill that combined funding for State Capitol repairs and an income tax cut.