Eugene Volokh of The Volokh Conspiracy has a short essay on denying the vote to felons:
First, note that the Constitution never secures a right to vote, the way it secures a right to free speech or a right to keep and bear arms. It leaves the matter to each state, and provides that, even in federal elections, who may vote shall be determined by whom each state allows to vote in state elections. Of course, various amendments have barred the government from discriminating based on race, sex, payment of poll tax, and age (over 18); but no constitutional text goes beyond that.
The Supreme Court has interpreted the Equal Protection Clause, in section 1 of the Fourteenth Amendment, as generally requiring “strict scrutiny” of laws that discriminate in voting (including when they use criteria that would be allowed in other contexts). But right there in section 2 of the Fourteenth Amendment is a provision that expressly contemplates states’ denying people the right to vote based on criminal record.
But when the right to vote at any election for the choice of electors for President and Vice President of the United States, Representatives in Congress, the Executive and Judicial officers of a State, or the members of the Legislature thereof, is denied to any of the male inhabitants of such State, being twenty-one years of age, and citizens of the United States, or in any way abridged, except for participation in rebellion, or other crime, the basis of representation therein shall be reduced in the proportion which the number of such male citizens shall bear to the whole number of male citizens twenty-one years of age in such State. [Emphasis added.]
It hadn’t occurred to me wonder if we really had a Federally secured right to vote, so this is interesting.