JEFFERSON CITY, Mo. (AP) -- Critics on Friday challenged the ballot summary for a proposed amendment to the Missouri Constitution that would clear the way to require voters to show photo identification at the polls.

The Republican-led Legislature passed the constitutional amendment last year and targeted it for this year's ballot. The measure would permit separate legislation that requires a photo ID and establishes an early voting period. Opponents contend the ballot summary developed by the Legislature is misleading and unfair.

"This is the worst one I've ever seen, by far the worst one I have ever seen. It fails under any standard," attorney Heidi Doerhoff Vollet said. "It's just false and it's wrong, and it needs to be corrected."

The ballot title approved by the Legislature asks voters: "Shall the Missouri Constitution be amended to adopt the Voter Protection Act and allow the General Assembly to provide by general law for advance voting prior to election day, voter photo identification requirements, and voter requirements based on whether one appears to vote in person or by absentee ballot?"

The phrase "Voter Protection Act" never actually appears in the constitutional amendment. Critics also contend the ballot summary is misleading because the Legislature already has authority to enact early voting laws and the measure would actually set limits on advance voting.

Cole County Circuit Judge Pat Joyce heard arguments Friday in the case, which involves two lawsuits. Vollett is handling one challenge, while the other lawsuit was filed by more than a half-dozen plaintiffs represented by the American Civil Liberties Union.

Deputy solicitor general Jeremiah Morgan defended the ballot summary. He acknowledged the phrase "Voter Protection Act" in the summary implies a title for a specific measure but said the problem easily could be fixed and was not sufficient to make the entire summary unfair. He also argued that mentioning the ability to create an early voting period is not a false description of the constitutional amendment.

"Clearly the Legislature felt that there was a need to be specific as to what was allowed," Morgan said.

Morgan said that if Joyce does not uphold the summary, then the courts could edit it or send the proposal back for lawmakers to revise. Attorneys challenging the ballot summary said significant changes are needed.

"Just about every word after 'shall the Missouri Constitution be amended to' would need to be changed," said Tony Rothert, an attorney for the American Civil Liberties Union. "So this would not be minor tweak, it would be a complete re-do."

Defendants include the Republican leaders of the House and Senate, the sponsor of the constitutional amendment and the secretary of state.

Barbara Wood, the general counsel for the secretary of state's office, said it agrees with opponents of the ballot summary and urged Joyce to conclude the summary is insufficient and unfair. Democratic Secretary of State Robin Carnahan has opposed past attempts to require a photo ID to vote.

Last year, lawmakers passed both the proposed constitutional amendment and separate legislation that would have enacted the photo ID requirement and early voting period. Democratic Gov. Jay Nixon vetoed the separate bill.

Missouri lawmakers have tried previously to require a photo ID for voters. Lawmakers in 2006 passed a law creating the requirement that was signed by Republican then-Gov. Matt Blunt. However, the Missouri Supreme Court concluded the law violated the fundamental right to vote and struck it down.