Technically the next-lower (Circuit Court of Appeals) decision stands in a tie, but it's fairly unlikely to happen that way, normally for anything that tough, there would be more than two opinions and the decision would be drawn from the points make in the most of them when taken all together; though not an even split, Roe v. Wade was a case where there was no majority opinion and therefore what it really means as legal precedent beyond the bare bottom-line outcome remains highly debatable.