Heinlein wrote many essays on the right to vote, which present many ideas on how the franchise should be earned. Starship Troopers (The book, not the movie) is essentially a political treastise on citizenship. BTW, before anyone reads it and gets the idea that he thought military service was the only way to win the franchise, read it again. His idea was federal service in some form, meaning anyone (not just those meeting the stringent requirements for military service) could earn the franchise, be it as an accountant or as a grunt, they just had to volunteer to do SOMETHING in federal service. Other ideas he had were a current events test prior to entering the voting booth (somtehing like the USA today headlines for the past 2 days, etc) or solve a simple math problem , just anything to prove that you were interested and informed. The founding fathers never meant for the US to be a democracy, they meant it to be a representative republic.