(As amended Dec. 29, 1948, eff. Oct. 20, 1949; Mar. 30, 1970, eff. July 1, 1970; Apr. 29, 1980, eff. Aug. 1, 1980; Pub. L. 96–481, § 205(a), Oct. 21, 1980, 94 Stat. 2330, eff. Oct. 1, 1981; Mar. 2, 1987, eff. Aug. 1, 1987; Apr. 22, 1993, eff. Dec. 1, 1993; Apr. 17, 2000, eff. Dec. 1, 2000; Apr. 12, 2006, eff. Dec. 1, 2006; Apr. 30, 2007, eff. Dec. 1, 2007; Apr. 16, 2013, eff. Dec. 1, 2013; Apr. 29, 2015, eff. Dec. 1, 2015.)