From a 1944 Alabama Supreme Court decision, Alabama State Federation of Labor v. McAdory, 18 So.2d 810, 815 (Ala. 1944):
legislative power is not derived either from the state or federal constitutions. These instruments are only limitations upon the power. Apart from limitations imposed by these fundamental charters of government, the power of the legislature has no bounds and is as plenary as that of the British Parliament.
That quote is the source of the court’s oft-mentioned strong presumption that legislative acts are constitutional.