Aereo is a web-based service that provides local TV signals to customers at a very low cost. TV networks have argued that Aereo is violating copyright by re-transmitting their product without consent. Lower courts have sided with Aereo. It'll now go to the U.S. Supreme Court. Were Aereo to prevail with SCOTUS, it will dramatically change the broadcast industry.
An Aereo win would call into question the law that currently requires local TV stations to negotiate re-transmission rights with cable TV and satellite companies. It might also mean television networks would no longer see the need for affiliate terrestial television stations.