Folks, slavery was “not a law, too”. Slavery was a practice that DID NOT RUN AFOUL of existing laws in many states–it was not a single law and most certainly not a federal law duly passed by Congress and validated by the courts. It was, in fact, a practice that ran afoul of laws in other states. And then there was a body of court decisions dealing with the rights of slave owners when the people they enslaved ran away from states where owning them was permissible under the law to the states where it was not. These also were not laws, as such, but a body of common law directing the application of conflicting laws.
Although it’s often referred to as a court decision legitimizing slavery, the Dred Scott decision is not so clear. There’s a lot of ink spilled trying to determine precisely what the holding of the case even was–given that it was nine separate opinions, with all seven justices in the majority giving different reasons for their decision. Generally, people take the case to mean what Taney said: that slaves and their descendants could not be citizens, no matter whether they were in free or slave states and that Congress could not choose for new states whether it would allow or prohibit slavery, based upon how territories were governed prior to becoming states.
So again, slavery was not a law. It was a practice–either prohibited or permitted–but not at the federal level. It would, in fact, have been perfectly plausible for a state to have no law regarding slavery at all, just as many currently went for years without laws about using cellphones while you’re driving or whether marriage licenses could be issued to interracial couples.
The Thirteenth Amendment did “repeal slavery laws” as much as it created a new rule: Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction. Sure, yes, under the amendment any law permitting slavery was now unconstitutional, but not repealed. States had to do that themselves. And then it gave Congress the authority to enact laws to prohibit slavery, which Taney, but not the entire Court, had said that it had no authority to do.
So, when someone points out that the Affordable Care Act is the law, and has been adjudicated Constitutional, and then says “Deal with it!” You really should not respond “So was slavery!” Because, no, slavery was not a law.