The congress has the right and the ability to stretch laws based on the validity in time. For example, when the constitution was written, congress had the right to establish an army and a navy. Well in 1947 that all changed because the air force was established. We all know that besides the french and their hot air balloons there were no air forces back in the late 1700's. However, under the elastic clause it is also implied that congress has the right to establish and grow an air force.