Following the Supreme Court’s ruling in favor of the Patient Protection and Affordable Care Act (ACA) and its lynchpin—the individual mandate—my colleague Josh Bivens noted all the ways conservatives have tried to keep health care from being delivered efficiently, notably by blocking government from using its monopsony power and economies of scale wisely. This, of course, is difficult to square with conservatives’ professed concerns about public debt, because rapidly rising health costs are, by far, the single biggest impediment to stabilizing long-run public debt (if the economy operates at full potential over this long-run). Political opportunism aside, reasonable policy should unequivocally aim to lower health care cost-growth; so here’s some evidence worth revisiting on the comparative efficiency of public versus private provision of health care.

The United States has a patchwork health care system of universal single-payer insurance for seniors (Medicare), publicly funded health coverage for the disabled and poor children and seniors (Medicaid and SCHIP), a rapidly unraveling system of employer-sponsored health insurance, fragmented private self-insurance markets, and 49 million non-elderly Americans (under the age of 65) without any health insurance. It’s important to note that the ACA was already a preemptive compromise with those opposed to a much more expansive role of government in directly financing health care. This, of course, doesn’t stop its opponents from lambasting it as a “government takeover,” but the ACA actually preserved the basic (inelegant) structure of American health care, seeking to fill in its gaps rather than a total overhaul. This makes its cost-containment provisions subject to much variability—some may work very well to restrain growth while others might not. And it also means that a clear, evidence-based tool for restraining these costs was left on the table: direct public provision of care and financing of costs.

By using its monopsony power and economies of scale gained by insuring tens of millions of people, public health programs have done a better job at restraining costs than private insurers. For example, since 1970, cost growth in inflation-adjusted Medicare spending per beneficiary has averaged 4.5 percent annually, versus 5.7 percent for private insurers. This underlying trend has been remarkably consistent over time: The 10-year rolling average of annual per enrollee cost growth for all benefits provided by private health insurers has exceeded that of Medicare in 28 of the past 31 years.

This divergent rate of cost growth compounds markedly over time. Since 1969, cumulative growth in private insurance spending per beneficiary has increased 60.8 percent more than that of Medicare.

And as I noted a while back, the Congressional Budget Office has estimated that Medicare is 11 percent cheaper than an actuarially equivalent private insurance plan, an efficiency premium that will similarly compound with time: Fee-for-service Medicare is projected to be at least 29 percent cheaper than an equivalent private insurance plan by 2030 (relative to CBO’s alternative fiscal scenario for the long-term budget outlook).

The ACA is projected to expand coverage to some 30-33 million additional non-elderly Americans by the end of the decade, a critical step for risk-pooling, increasing cost-saving preventive care, and decreasing uncompensated care costs passed along to providers and policy holders. It also included ambitious reforms to control costs (particularly the Independent Payment Advisory Board, or IPAB), but too many provisions leveraging the public sector’s ability to directly contain costs—notably offering a public insurance option (e.g., Medicare buy-in) and negotiating Medicare Part D prescription drug prices with pharmaceutical companies (as is done for Medicaid)—were lobbied out of the bill. Even though stronger cost-containments could have been included, the Supreme Court’s ruling in favor of the ACA is a major victory for long-run fiscal sustainability, as health reform is projected to reduce annual long-run budget deficits by roughly half-a-percentage point of GDP.

The ACA is a momentous step toward more efficient and comprehensive health care coverage in the United States, but reform will undoubtedly remain a work in progress—particularly as the various cost-containment provisions in the ACA are evaluated and successes merit replication. Our experience over the last 40 years should guide policymakers as they inevitably go back to the drawing board on health care reform; and the evidence over this time overwhelmingly suggests that public provision of health care is more effective at containing excess cost growth and more efficient than private insurance provision.

Data from the Centers for Medicare and Medicaid Services’ National Health Expenditure Accounts Table 16, adjusted to constant 2011 dollars using CPI-U-RS.