Twenty-second Amendment to the United States Constitution
Some argue that the 22nd Amendment and 12th Amendment bar any two-term president from later serving as vice president as well as from succeeding to the presidency from any point in the presidential line of succession. Others contend that the original intent of the 12th Amendment concerns qualification for "service" (age, residence, and citizenship), while the 22nd Amendment, concerns qualifications for "election", and thus (strictly applying the text) a former two-term president is still eligible to "serve" as vice president (neither amendment restricts the number of times an individual can be elected to the vice presidency), and then succeed to the presidency to serve out the balance of the term (though prohibited from running for election to an additional term).
Leonard Peltier
Peltier was the candidate for the Peace and Freedom Party in the 2004 election for President of the United States. While numerous states have laws that prohibit prison inmates convicted of felonies from voting (Maine and Vermont are exceptions), the United States Constitution has no prohibition against felons being elected to federal offices, including President. The Peace and Freedom Party secured ballot status for Peltier only in California, where his presidential candidacy received 27,607 votes, approximately 0.2% of the vote in that state.