The issue is that the authority to govern comes from the powers presented by the constitution, and the powers the government has exercised to establish those laws is not founded on the powers it was provided. That makes the foundation of the law itself unsound. The Supreme court has unfortunately upheld the ACA and other such unfounded pieces of legislation, but they have also upended many intrinsic checks and balances in thier side of government as well, by doing such nasty things as making jury nullification no longer a right, but just a power. (A power you are not legally allowed to employ I might add.) and other such shenanigans. The term "Regulatory capture" comes to mind.
Simply because the pimply butted assholes in the fancy chairs on capitol hill say something is legal and substantiated, does not mean that it actually is. (See for instance, the drama over FISA courts, the NSA, and the people who actually wrote the patriot act.)
Because the constitution was never amended to permit that set of powers being weilded by the government, there is no legal foundation for them to produce that law, making the act of passing it illegal. I dont care what the law is about, they dont have the power to regulate domestic issues like that. That power is reserved to the individual citizens and to the individual states, as the citizens choose to allot to the states-- as written.
If they pass a constitutional amendment saying that they can be little dictators, and get the 2/3 majority signature, then what they do after that point is perfectly legal. Until they do so, it is not.
The thing is, there is formal Constitution and material constitution. Formal one is easy - its the Constitution and amendments. Material constitution of a country consists of much more than just a formal constitution, it consists of other acts of constitutional law (such as voting acts), decisions of the Supreme Court, legal principles and also natural law.
This means that the words of constitution can have their meaning shifted and changed with the progress of time. The very power of Supreme Court to determine constitutionality of act of governement is such thing. The meaning of judicial review was pretty much expanded to also include review of constitutionality of acts, even if the Constitution itself didnt change.
You could say the Supreme Court created such power for itself because it wasnt directly written in Constitution. But that would be wrong, because such power was implied as the SC reasoned. There is no need to have everything explicitly written in Constitution, and frankly it would be impossible. You have Supreme Court for determining what is still inside Constitution clauses and what is unconstitutional.