Birtherism is now officially a legal issue, as the eligibility of Sen. Ted Cruz to run for president will have a hearing Friday in Chicago, according to multiple news outlets.

According to CNN and ABC, a Cook County Circuit Court judge will hear a lawsuit brought by an Illinois voter who says Mr. Cruz is not a natural-born citizen, as the Constitution requires, because he was born in Canada.

Mr. Cruz has never denied being born in Canada, but maintains that the issue is ridiculous because under longstanding U.S. statutory law, he was automatically a U.S. citizen at birth because his mother was a U.S. citizen.

But Lawrence Joyce maintains otherwise and had filed an earlier case with the Illinois Board of Elections, only to have it rejected earlier this month.

Mr. Joyce told WBBM radio that he supports retired neurosurgeon Ben Carson and has not been in consultation with the campaign of real estate mogul Donald Trump, who has repeatedly said Mr. Cruz might not be eligible to take office.

Still, Mr. Joyce told the station, “my case presents the perfect opportunity for Donald Trump himself to step forward and bring the matter to court personally.”

Like Mr. Trump though, Mr. Joyce said his concern is that the eligibility issue lie unresolved during Republican primaries, thus letting the Democrats take advantage of it after a potential Cruz nomination, when it’d be too late.

“At that point, all of his fundraising would dry up. And his support in the polls would drop dramatically. He may be forced at that point to resign the nomination,” Mr. Joyce said.

At a CNN town-hall meeting Wednesday night, the issue was brought up by a voter to Mr. Cruz, who calmly said the legal issue has been “clear from the very first days of the republic.”

“The child of a U.S. citizen born abroad is a U.S. citizen,” Mr. Cruz said, noting that the law on the matter dates from the Founding generation.

“Indeed the very first Congress … wrote the very first laws on citizenship. And they explicitly defined the child of a U.S. citizen born abroad as a natural-born citizen.”

The Texan added that he had never been naturalized and that previous presidential hopefuls such as John McCain (born in Panama, to military service members) and George Romney (born in Mexico to Mormon missionaries) were uncontroversially eligible.