No, the progressive decrease in potential energy of a freely falling object does not violate the law of conservation of energy. The law of conservation of energy states that energy cannot be created or destroyed, only transformed. As a falling object loses potential energy due to decreasing height, that energy is not lost but is converted into kinetic energy, which increases as the object accelerates due to gravity. The total mechanical energy (potential + kinetic) of the falling object remains constant throughout its fall.