Twenty-second Amendment to the United States Constitution
As worded, the primary focus of the 22nd Amendment is on limiting individuals twice elected to the presidency from being elected again. Due to this, several issues could be raised regarding the amendment's meaning and application, especially in relation to the 12th Amendment, ratified in 1804, which states, "But no person constitutionally ineligible to the office of President shall be eligible to that of Vice-President of the United States". While it is clear that under the 12th Amendment the original constitutional qualifications of age, citizenship, and residency apply to both the president and vice president, it is unclear whether someone who is ineligible to be elected president could be elected vice president. Because of this apparent ambiguity, there may be a loophole in the 22nd Amendment whereby a two-term former-president could be elected vice president and then succeed to the presidency as a result of the incumbent's death, resignation, or removal from office (or even succeed to the presidency from some other stated office in the presidential line of succession).
United States presidential primary
In many states, only voters registered with a party may vote in that party's primary, known as a closed primary. In some states, a semi-closed primary is practiced, in which voters unaffiliated with a party (independents) may choose a party primary in which to vote. In an open primary, any voter may vote in any party's primary. In all of these systems, a voter may participate in only one primary; that is, a voter who casts a vote for a candidate standing for the Republican nomination for president cannot cast a vote for a candidate standing for the Democratic nomination, or vice versa. A few states once staged a blanket primary, in which voters could vote for one candidate in multiple primaries, but the practice was struck down by the U.S. Supreme Court in the 2000 case of "California Democratic Party v. Jones" as violating the freedom of assembly guaranteed by the First Amendment.