A greater struggle occurred over Commonwealth legislation in the field of aviation. Commonwealth regulation is based on the interstate and international trade and commerce power. Prima facie, it does not cover intrastate aviation. However, a purely intrastate aviation industry is no longer economically feasible and separate systems of state regulation pose safety concerns. As a result, the High Court held that all aviation has an interstate character, placing it within Commonwealth legislative power. In 1937 a referendum was submitted to the people giving the Commonwealth power over aviation, and that the referendum was rejected by the people. The rejection of a power by the people has never persuaded the Court that the Commonwealth should not exercise the power.