A significant part of the excitement behind the Bernie Sanders’ run at the presidency was his unreserved support of “Medicare for all.” That is, mirroring systems like the UK’s National Health Service, he wants the highest levels of government to be the “single-payer” of a US health care system for everyone.

His advocacy has paid off. The Democratic platform supported a government-run “public option” under the Affordable Care Act, and Hillary Clinton publicly supported moving Medicare eligibility from 65 years old to 50. Both of these proposals were politically unviable just a few years ago.

Supporters of a single-payer, NHS-like system—perhaps counter-intuitively—have been energized by the very serious structural problems of the Affordable Care Act. It leaves many millions living in the United States without insurance. Its health insurance exchanges are a disaster. And the New York Times reported just last week, despite promises of the opposite, ACA premiums continue to skyrocket.

Conservatives and liberals can agree that health care reform has been “hobbled by the political compromises made to get it passed”—and that there will likely be a reform of the reform.

Single-payer activists like Howard Dean initially opposed it as “a bigger bailout for the insurance industry than AIG” now see the ACA’s passage (and its problems) as a means of getting to our own National Health Service.

Many Americans can’t imagine what could be wrong with this. The UK spends less money and has better health outcomes than we do. It covers everyone, even those merely visiting the country. What’s not to like?

But most countries which have something like a National Health Service are dramatically smaller and more homogenous than the US. We have a deep commitment to pluralism of ideas, including ideas about health care. This area of life intersects with some of our most serious and deeply-held values, and our culture attempts to create space for very different kinds of people authentically to live out these values.

A “one size fits all” approach, given our commitment to diversity and plurality, is unlikely to succeed.

Another concern is that the profits which drive up health care costs in the US actually are also the reason we are the leader in developing life-saving medical innovations. Yes, other countries spend less and have better outcomes—but they outsource a disproportionate amount of the costs of research and development.

Furthermore, half the US federal budget is already spoken for with fixed entitlement commitments, and this already large number would skyrocket with a single-payer system.

People in the developed West are living longer but (even in the UK) getting less healthy. Couple this with rising health care costs and (even in the US) fewer, younger, healthy people around to pay taxes and fit the bill for older, sicker people, and the tax burden on Americans in a country with a single-payer system becomes difficult to imagine.

The UK tax burden is already so high that they are choosing to deal with the NHS’ monstrous budget shortfall by making difficult decisions in rationing health care. Indeed, highly respected British physicians are saying that the system is going to face “crippling pain” because of rationing in the very near future.

We learned last week about one dramatic example of such pain: the NHS will ration care based on how fat patients are. If you live in North Yorkshire and have a Body Mass Index of 30 or above, for instance, you “will be barred from most surgery for up to a year amid increasingly desperate measures to plug a funding black hole.”

And this is just the latest dramatic example of NHS rationing. The red-tape and wait times associated with getting needed procedures (everything from cancer drugs to heart surgeries) is such that treatment is de facto rationed when patients die waiting for care.

The Catholic Church is correct: access to health care is the moral right of every single human being. But as we’ve seen with other issues (like the death penalty or abortion), how the Church’s moral claim plays out in any given cultural or legal context depends on a number of slippery and changeable social factors.

There is, therefore, no Catholic teaching on what system of health care distribution the US should adopt in the early 21st Century. Coming up with such a policy requires the prudential judgment of people of good will doing a delicate balancing act with multiple, important, often-conflicting goods.

My first book argued that, given the finitude of human nature and of human resources, we will never not be rationing health care. Governments do it. Insurance companies do it. Families do it. All things considered, prudential judgement may mean enacting a single-payer system. We may need to accept the very serious downsides in order to get to the wonderful good of covering everyone with a basic level of care.

But advocates of a single-payer system should be more honest about these downsides. And Catholics should acknowledge that the right to health care can be legitimately expressed by more than one kind of policy.

Charles C. Camosy is Associate Professor of Theological and Social Ethics at Fordham University and author of Too Expensive to Treat?