Which is exactly what the lower state court did in awarding Scott his freedom! The Missouri Supreme court with a majority pro slavery bench overturned that verdict and said in effect that we used to respect other states laws, but times have changed and we will no longer respect them even though Article IV says we have to.
Article IV says states have to respect other states slave laws. I take that to mean that in a contest between freedom laws of a free state, and slave laws of a slave state, the slave laws must always prevail.
Yeah, that's ugly, but that's what it says, and if Northern states didn't agree to it, they wouldn't have had to abide by it.
The lower courts were apparently unaware that laws freeing slaves, and laws holding them in bondage were inherently unequal in the requirements of the Constitution, with the slave laws having the superior legal position.
Again, don't blame me for pointing this out, but that was the law of that era.