Back in 2012, pretty much everyone thought ObamaCare was going to be struck down as unconstitutional. The Obama admin had claimed, repeatedly, that the healthcare law was not a tax and that seemed to be the only way to justify its existence. Then, sadly, Justice John Roberts basically re-wrote the law, decided - despite the administration's own arguments - that Obama's signature law was a tax, and upheld it based upon Congressional taxation powers. It was about as baffling a decision as anyone has ever seen and, obviously, it's been controversial ever since.
Now, a coalition of 20 states has filed a lawsuit arguing that ObamaCare is no longer unconstitutional.