Washington(CNN) Members of the Electoral College get their authority from the US Constitution, not states, and shouldn't be punished for voting their conscience when it comes to presidential nominees, Harvard professor Lawrence Lessig told the Supreme Court in a court filing Monday.
The case, which the justices will hear next month with a ruling expected by July, adds another hot-button political issue to the Supreme Court's docket in the middle of the presidential election.
In theory, a Supreme Court ruling allowing so-called "faithless electors" would add a new level of uncertainty to the race, with no guarantee the winner of the popular vote in a state would get the state's full number of electoral votes.
The 2016 election turned out not to be that close, with President Donald Trump winning over 300 electoral votes, but the situation could be much different this year if the contest is closer.
Hillary Clinton won the state of Washington in the 2016 presidential election but did not collect all of the state's 12 electoral votes. Instead, three votes went to former Secretary of State Colin Powell and one to anti-Keystone XL pipeline protestor Faith Spotted Eagle.
In Colorado, an elector who also attempted to defect from Clinton and select Ohio Republican Gov. John Kasich was replaced with a Clinton voter.
Last May, the Washington state Supreme Court held that the state could regulate the vote of an elector either directly or indirectly, upholding a $1,000 fine for the Clinton defectors. In August, a federal appeals court said a similar Colorado law was unconstitutional. Now, the Supreme Court will have its turn.
"This Court should restore the practice that has governed for more than 220 years and make clear that while states have plenary power 'to appoint' electors, it is the 'Electors' who have the power 'to vote' free of state control," wrote Lessig of the advocacy group Equal Citizens, representing the Colorado elector and the Powell voters.
A state must appoint electors, but once that happens, Lessig argues, its power ends.
Most states currently require some kind of a pledge from an elector to vote for the party's candidate who won the popular vote in the state. Overall, 10 of the 538 presidential electors in 2016 voted or attempted to vote for someone other than their pledged candidate.
Lessig suggests a hypothetical to the Supreme Court, asking that if states are allowed to enforce who electors vote for, there may not be a way to stop them from adding other conditions such as blocking candidates who don't release their tax returns.
"If a state has the power to direct electors to vote consistent with the election returns, a state has the power to forbid electors from voting for candidates who fail to release their taxes returns, who fail to visit the electors' state, or who fail to commit to any political position deemed by a state legislature to be important and correct."
Washington state Attorney General Bob Ferguson says the "real" purpose of the lawsuit is to eventually end the Electoral College altogether.
"Accepting their view would mean that only 538 Americans -- members of the Electoral College -- have a say in who should be President; everything else is simply advisory," Ferguson wrote earlier this year in urging the Supreme Court not to take up the case. "Their avowed purpose in seeking this ruling is to destroy public faith in the Electoral College so that the people decide to do away with it."