Most cases that are heard in the Supreme Court of either the states or the Supreme Court of the United States are overturned. This is especially true of the states. If the state Supreme Court agrees with the state appeals court, they simply don't accept the case and the ruling of the appeals court stands. The fact that the Illinois Supreme Court took the case is a good sign.
With the U.S. Supreme Court, they are usually deciding conflicting Circuit appeals of a similar federal question. One Circuit is going to get overturned while another Circuit gets affirmed. The coastal Circuits are issuing liberal verdicts while the midwest Circuits are issuing conservative verdicts for the same federal question. When that happens, it is up to SCOTUS to decide. Otherwise, there is not a national legal consensus.