When evaluating the ethics of the Affordable Care Act (ACA), there are several distinct parts of the original legislation, passed into law in 2010, that one must consider. First, let us start with the part of the law that prevents health insurance companies from discriminating against individuals with "pre-existing health conditions." Before passage of the ACA, healthcare companies could and routinely did deny coverage or charge exorbitant rates to individuals with both chronic and acute medical conditions, such as cancer, depression, diabetes, Multiple Sclerosis, HIV, and even pregnancy. Allowing health insurance companies to either deny coverage to sick people or to charge those sick people extra in order to obtain coverage was certainly controversial and, in many people's minds, unethical. In most other developed nations (including most of Europe, Japan, South Korea, and so on), such practices do not exist, because healthcare is considered a right, rather than a privilege, extended to all citizens and paid for by the government. Yet before the ACA, in the United States, that practice was not illegal, but in fact quite standard.
In practice, this meant that if an individual had a treatable form of cancer, say leukemia, but could not afford the very high premiums that the health insurance companies wanted that person to pay, or if that person was completely shut out of the healthcare insurance market by insurers who deemed covering such illnesses unprofitable no matter what, then that person would likely die of a disease that was medically treatable. To get at the heart of the moral problem here, it is important to understand that another individual with cancer, if he or she had plenty of money, could pay "out of pocket" for treatment and escape the almost certain death sentence that a less affluent individual would face with the same medical condition. In other words, before passage of the ACA, those who were affluent and had pre-existing conditions could survive medical conditions that less affluent patients could not. Is that an ethical system?
Another important provision of the ACA, which has since been overturned by Congress, was the so-called "Individual Mandate." This provision stated that every adult had to buy health insurance, and if they did not, they would have to pay a fine. The purpose of this provision was to incentivize young, healthy adults, who often went without health insurance, to purchase it. That way, the pool of insured people would be on average healthier and younger than before, thus lowering health insurance premiums for the population at large. The moral question here is a little more complex, but essentially it boils down to this: if one does not have health insurance and becomes ill or gets in an accident, that person nevertheless gets treated in an emergency room and is sometimes hospitalized, given surgery, and so on. These life-saving services are provided by hospitals at an immense cost to taxpayers. Those who were and are uninsured and unable to pay for the hospital bills incurred by unexpected, acute illnesses (like appendicitis) or injuries (car accidents) cause healthcare costs and premiums for all other Americans to rise. Because medical providers are required to provide emergency treatment to these acutely ill patients regardless of their ability to pay, the cost for treating such uninsured individuals gets passed on to both taxpayers and those who pay insurance premiums. In fact, one of the major cost drivers for insurance premiums is the pooled cost of paying for the so-called "freeloaders" who choose to remain uninsured. The individual mandate was designed to prevent this kind of economic "freeloading." The rationale for requiring everyone to get insurance was that everyone uses the healthcare system at some point, so everyone should pay in to some extent.
Some people, particularly those with conservative politics, viewed the individual mandate as an overreach by the federal government. Some younger healthcare consumers who wanted to "take their chances" also initially viewed the mandate as unfair. Had the mandate not been coupled with vast subsidies that help people to pay for their insurance premiums through the so-called Public Exchanges, which are run by the federal government and by various state governments, this argument would have probably been stronger from an ethical standpoint.
Yet the subsidies provided by the ACA to both low- and middle-income earners to make the cost of health are insurance affordable attracted an additional 30 million Americans into the system, thereby leaving many fewer Americans uninsured. Ethically speaking, the argument went, the individual mandate was a net benefit for the "greater good." Those who opposed it argued that the mandate infringed on individual liberty. One could probably argue either side, depending on his or her political philosophy.
From an ethical standpoint, however, having a larger proportion of the population covered by health insurance is surely a good thing, because it means fewer will suffer or go bankrupt as a result of illness. Additionally, the ACA expanded Medicare, which made health insurance for millions more Americans living near or below the poverty line free. This further expansion of healthcare coverage also would seem to be an ethically positive move.
That said, many conservative politicians and voters were outraged by the fact that taxes for more affluent citizens went up to pay for this expanded healthcare coverage for less affluent people. The ethical quandary posed by this type of legislation begs the question of whether a "just society" should take care of its most vulnerable citizens by taxing its more affluent citizens. That is a question that remains hotly debated in our national politics.