The Supreme Court decision in Oregon v. Mitchell lead directly to the passing of the 26th Amendment. The Supreme Court ruled that the 18-year-old voting age requirement, established in the Voting Rights Act Amendments of 1970, was valid for national elections, but not valid for state or local elections.
In Oregon v. Mitchell, the states of Oregon, Texas, and Idaho sued Attorney General John Mitchell and challenged the Voting Rights Act Amendments of 1970, which had recently lowered the voting age to 18. These states argued that only individual states and not Congress has the legal authority to set qualification rules for voters in state and local elections, notes Pearson Prentice Hall. The decision in Oregon v. Mitchell initially looked like a victory for the states, but most states still faced difficulty and added expenses in tracking eligible voters in various elections.
Only four states allowed individuals under 21 years of age the right to vote prior to the 26th Amendment. For example, a 19-year-old was allowed to vote for president and vice president but not for state officials who were up for election at the same time. In 1971, the states urged Congress to adopt a proposed, constitutional amendment to set a uniform national voting age of 18 in all elections, which thereafter was ratified by the states, notes Cornell University Law School, Legal Information Institute.