Ted Cruz's 'natural-born' citizenship will be challenged in front of a judge for the first time

Top-tier presidential candidate and Senator Ted Cruz (R-Texas) is facing a legal challenge to his candidacy based on his Canadian birth - and it's not from GOP front-runner Donald Trump.

On Friday, an Illinois judge will hear arguments from a voter who claims Cruz should be disqualified because he's not a "natural-born" citizen, USA Today reported.

The case against Cruz, brought forth by Lawrence Joyce of Illinois, will be heard by Judge Maureen Ward Kirby of the Circuit Court of Cook County in Chicago.

Joyce made a previous plea to the Illinois Board of Elections earlier this year, but had his suit dismissed on February 1. After appealing, he was granted Friday's hearing.

Article II, Section 1 of the Constitution states that "No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President."

The definition of "natural-born citizen" has never been definitively addressed by the Supreme Court, leading to disputes over whether a candidate has to be born on US soil in order to be President.

Cruz, for his part, contends that he is a "natural-born citizen" because his mother was born in Delaware. He once had dual citizenship with Canada, but said in 2013 that he would renounce his Canadian citizenship.

That has not stopped some of his rivals - including Donald Trump - from challenging his eligibility. Trump, the GOP frontrunner, has threatened lawsuits against Cruz at various points during the race.

A similar challenge to Joyce's was filed on Thursday with New York's Board of Elections, per USA Today. Cruz also faces a federal lawsuit filed in Texas questioning his eligibility.

Joyce said he is backing Republican contender Ben Carson and hasn't colluded with Trump's campaign.

"I tried to talk myself out of it and was unable to do so," Joyce told USA Today. "It's plain as day that Ted Cruz is not a natural born citizen of the United States."

During Wednesday's CNN Republican presidential town hall, Cruz once again defended himself.

"I never breathed a breath of air on this planet when I was not a U.S. citizen," Cruz told the audience, calling any claims to the contrary "political mischief."

"It was the act of being born that made me a US citizen."

Adam Winkler, a constitutional law professor at UCLA, said "there are good arguments on both sides" when it comes to the question of Cruz's eligibility.

"I think at the end of the day, the purpose of that language was to ensure that no one was elected president who had loyalties to another country," Winkler said in an interview with Business Insider. "I believe that in a close case like Ted Cruz's, that purpose would not be served by keeping him off the ballot."