Pombo is especially known for his defense of private property rights. This was spurred by the Southern Pacific Railroad's abandonment of the Altamont Pass route through Tracy. Pombo owned land adjacent to the abandoned railroad line. Pombo argued that the abandoned easement should legally revert to the adjacent property owners (such as himself) rather than to the local park district. He argued that as the easement was granted based on a promise that the land would be used for railroad purposes only, that the easements ended entirely when they were abandoned. Pombo's case resulted in Congress passing the Rails to Trails Act.