JEFFERSON CITY, Mo. -- Missouri will not use 85 new ballot drop boxes for the Nov. 3 election out of concern that confusion over a new state voting law might invalidate some mail-in ballots, election officials said.

A law approved by the Legislature this year requires people to notarize their mail-in ballots, then mail completed ballots back to local election officials, with some exceptions. That means mail-in ballots put into a drop box would not be counted, the St. Louis Post-Dispatch reported.

The law does not affect absentee ballots, which may be returned by mail or in person. Voters do not need an excuse to receive a mail-in ballot but must cite one of seven reasons included in the law to receive an absentee ballot.

Maura Browning, spokeswoman for Republican Secretary of State Jay Ashcroft, said most of the new drop boxes were ordered before the Legislature changed the election laws, and they were all ordered before GOP Gov. Mike Parson signed the proposal.

She noted that in previous elections all alternative ballots could be returned in person but said the state is "operating under a whole other set of rules," for November's election.

"This is not about us trying to make it difficult for voters," Browning said. "We're trying to ensure that their votes count."

At $501 per box, the order will cost $42,585. Browning said the office will use money from the Help America Vote Act to pay for the boxes. She said the new laws are in effect only for this year, so the drop boxes could be used in future elections.

The requirement that mail-in ballots cannot be dropped off in person was one of five Missouri election laws cited in a lawsuit filed Thursday in Cole County challenging their constitutionality.

The lawsuit was filed by three St. Louis-area voters and the Washington, D.C., voting rights organization American Women.

"Under the Mail-Return Mandate, a well-intentioned and otherwise qualified Mail-In voter who reasonably decides to drop off her ballot at her local polling place on Election Day -- perhaps because a family member, an Absentee voter, plans to do the same -- would be completely disenfranchised," according to the lawsuit.

The lawsuit also challenges a Missouri law that invalidates any ballot that does not arrive in election officials' offices by 7 p.m. on Election Day, even if the ballot is postmarked by Election Day.

The lawsuit also contends that because voters using the new method must return ballots by mail, the Postal Service might be overwhelmed.

The Postal Service has recommended voters send ballots back by mail no later than Oct. 27, a week before the election, to ensure they are returned to election officials in time to be counted.