WASHINGTON (CN) – The Supreme Court agreed Friday to hear a case on whether Electoral College voters are legally bound to cast their ballot for president in line with their state’s popular vote.

During the 2016 election, 10 of the 545 presidential electors went rogue and voted for a candidate who was not their party’s nominee, the highest number of so-called “faithless electors” in U.S. history. Seven successfully cast their votes, while three were replaced by other electors on the day of voting.

The electoral vote on election night in 2016 was expected to break down to 306 for Donald Trump and 232 for Clinton. Instead, electors cast their votes 304-227 with Trump as the victor.

Three Democrat party members in Washington state who should have cast their vote for Clinton instead voted for Colin Powell, the former secretary of state under President George W. Bush. Ten days later, the three electors were fined $1,000 under a state law mandating they vote for the party nominee.

The three electors appealed but the Washington Supreme Court ruled 8-1 to uphold the issuance of the fines last May. Justice Steven González pushed back against the majority, finding that states have only the authority to appoint, not to control, the electors.

“This ‘leav[es] the electors with the discretion to vote their conscience,’” González’s dissenting opinion states, according to the electors’ petition to the U.S. Supreme Court.

The petitioners now will take their argument to the nation’s highest court in the current term, meaning the case will be decided by the end of June. They claim that the penalty was the first time in history that presidential electors were fined, and point out they are not the first to cast an unpredicted vote.

“Indeed, from the birth of the republic, electors have cast their ballots contrary to legislative direction or expectation without penalty or legal consequence,” the petition states.

They had also urged the justices to consider arguments on the Electoral College before drawing too close to Election Day, or worse, in the case of a contested presidential election.

“The Supreme Court should avoid that dangerous possibility. This case gives the court the rare opportunity to decide a constitutional question related to presidential selection in a non-emergency setting,” the petition states.

More than half of U.S. states have laws like the one the electors are challenging in Washington. The Supreme Court ruling will not alter the Electoral College outcome of the 2016 election but may reshape the role of presidential electors.

The petition argues that the ruling will “conclusively determine” the validity of laws that “restrict elector discretion.”

“Then, if the court’s decision affects any future election, it will do so only as a matter of constitutional principle, not partisan affiliation. That makes this court’s intervention now critical,” the petition states.

In agreeing to hear the case Chiafalo v. Washington, the Supreme Court consolidated it with a another case out of the Tenth Circuit, Baca v. Colorado Department of State.

Per their custom, the justices did not comment on their decision to grant review.