They ruled on a related claim in 2006.
The crux of the matter is how much money Smith was entitled to from the estate of her elderly husband, Texas millionaire J. Howard Marshall II, but essentially the Supreme Court took an interest because of the morass of issues involving which court had the legitimacy to rule on the case.
Now both of the major parties in the case — Smith, and her former husband's son — are dead, even as the case drags on, fourteen years after it began. It is, as CNN notes, "the unusual scenario of two estates now fighting over the still-frozen assets of another estate." It's even more complicated because the case is being pushed by Howard K. Stern (also in the photo above), who is himself in court on charges that he conspired to keep Smith addicted to drugs, and that he used false names to get those drugs. But hey, he's not her baby's father. Because that would be really complicated.