By JONATHAN GRUBER | Professor of economics, Massachusetts Institute of Technology

On April 12, Massachusetts residents will celebrate the sixth anniversary of Governor Mitt Romney's historic health care reform. This reform transformed health care in my home state and served as the basis for the federal Affordable Care Act (ACA). Romney should be proudly joining in the celebration of a law he once viewed as a national model. Sadly, he is instead running away from it.

Governor Romney’s approach broke new ground with a transformative “three legged stool”: reforming insurance markets to protect the sick, subsidizing coverage to make it affordable for working families, and mandating broad participation to include both healthy and sick.

In particular, the individual mandate was a conservative idea that was proposed by Romney as a key linchpin of individual responsibility, preventing those who could afford insurance from a “free ride.” Conservatives were so proud of the adoption of their ideas that one of the only speakers at the signing of the Massachusetts law was from the Heritage Foundation.

And they were right to be proud, as reform has worked spectacularly. Massachusetts has covered two-thirds of its uninsured, and, relative to national trends, prices in the individual insurance market have fallen and employer-sponsored insurance coverage has risen, while public support is consistently above 60%.

In the past, Governor Romney saw the Massachusetts law as a possible national model. In 2009, he encouraged Republicans to propose a plan for universal coverage, saying, “I think what we did in Massachusetts is a good model to start from.” And the Obama Administration and Congressional Democrats agreed – despite the Republican origins of the individual mandate.

Make no mistake: the Affordable Care Act is based on Massachusetts’s success. The core of the ACA is the same “three legged stool” that was first developed in Massachusetts. Several of the architects of Massachusetts reform, including myself, worked closely with the Administration and Congress to translate the lessons from Massachusetts onto the national stage. And experts project that the ACA will have similar success, reducing the number of uninsured Americans by 30 million.

Indeed, this should be a proud moment for Governor Romney. Unfortunately, he has changed his mind and insists his approach won’t work at the federal level, leaving him in the disingenuous position of defending the Massachusetts reform while opposing its progeny.

Governor Romney’s attempt to distinguish the Massachusetts law he wrote from the national law he bitterly opposes makes no sense. First, he states that the ACA imposes a “one size fits all” model on states. But in fact the ACA leaves enormous state flexibility to design state insurance exchanges, so states are likely to have widely differing individual insurance markets.

Second, he criticizes the spending reductions and revenue increases in the ACA, highlighting that he didn’t raise taxes to finance reform. But he doesn’t acknowledge that this was possible because the Federal government paid for about half of the costs, and that the other half was financed by redirecting an existing Massachusetts tax. At the federal level we don’t have this luxury.

Third, Governor Romney criticizes the one place where the ACA is more ambitious than Massachusetts: health care cost control. Our state reform did not attempt to control underlying costs. In contrast, The ACA introduces a host of new mechanisms to try to reign in health care spending. But this is not a “government takeover” of health care. The ACA instead uses market incentives like health insurance exchanges, the end of tax subsidization of expensive plans, and changes in the structure of federal health insurance reimbursement to move us towards bending the health care cost curve.

Governor Romney has criticized these measures but offered nothing in their place. Instead, he recycles tired conservative ideas such as promoting health savings accounts – which have never been shown to lower health care cost growth, but do reduce use of preventive care and cost billions in lost revenue.

More strikingly, Governor Romney points to cross-state sales of insurance as a means of cost control. Not only is there no evidence that this would in any way reduce costs, it also highlights a fundamental contradiction. In the presence of cross-state insurance sales, states that wish to enforce fair pricing of insurance across healthy and sick can’t do so because the healthy will buy their insurance elsewhere. So the Governor’s proposal would undercut states’ rights at the same time that he criticizes the ACA for doing so.

I will always have enormous respect for Governor Romney for the success of his Massachusetts health care reform plan and the critical role it played in shaping the ACA. But I am disappointed to see the extent to which he contorts himself to try to draw false distinctions between the reforms, and the misleading and contradictory arguments that he makes in doing so.