The controversial individual mandate that was upheld Thursday by the U.S. Supreme Court stems back more than 20 years, believed to have originated with a prominent conservative think tank.

The mandate, requiring every American to purchase health insurance, appeared in a 1989 published proposal by Stuart M. Butler of the conservative Heritage Foundation called "Assuring Affordable Health Care for All Americans," which included a provision to "mandate all households to obtain adequate insurance."

The Heritage Foundation "substantially revised" its proposal four years later, according to a 1994 analysis by the Congressional Budget Office. But the idea of an individual health insurance mandate later appeared in two bills introduced by Republican lawmakers in 1993, according to the non-partisan research group ProCon.org. Among the supporters of the bills were senators Orrin Hatch, R-Utah, and Charles Grassley, R-Iowa, who today oppose the mandate under current law.

In 2006, Republican presidential candidate Mitt Romney, who was then governor of Massachusetts, signed off on a law requiring individuals of the state to purchase health insurance. American Bridge 21st Century, a Democratic opposition research group, on Wednesday released a 2006 video in which Romney says he is “very pleased” with the mandate.

“With regards to the individual mandate, the individual responsibility program that I proposed, I was very pleased that the compromise between the two houses includes the personal responsibility mandate. That is essential for bringing the health care costs down for everyone and getting everyone the health insurance they need," Romney says in the video.

In 2007, a bi-partisan Senate bill authored by Senators Bob Bennett, R-Utah, and Ron Wyden, D-Oregon, contained a mandate. In 2009, however, Republican senators declared such a provision “unconstitutional.”

During the 2008 presidential campaign, Obama expressed opposition to a mandate requiring all Americans to buy health care insurance. In a Feb. 28, 2008, interview on the Ellen DeGeneres show, Obama sought to distinguish himself from then-candidate Hillary Clinton by saying, "Both of us want to provide health care to all Americans. There’s a slight difference, and her plan is a good one. But, she mandates that everybody buy health care.

"She’d have the government force every individual to buy insurance and I don’t have such a mandate because I don’t think the problem is that people don’t want health insurance, it’s that they can’t afford it," Obama said. "So, I focus more on lowering costs. This is a modest difference. But, it’s one that she’s tried to elevate, arguing that because I don’t force people to buy health care that I’m not insuring everybody. Well, if things were that easy, I could mandate everybody to buy a house, and that would solve the problem of homelessness. It doesn't."

In 2010, Obama signed the Patient Protection and Affordable Care Act that put into place an individual mandate.