For example, a much stricter effort failed in the Missouri House last session, when lawmakers rejected a plan that would have allowed terminally ill patients to use the drug to relieve pain.

Signatures must come from registered voters, who fill out forms based on what county in Missouri they’re registered to vote in. Local election authorities are tasked with matching up the signatures on petitions with signatures in their own records.

Witnesses who helped gather or verify signatures on behalf of New Approach testified Monday that voters often don’t know what county they’re registered in. Sometimes, they argued, errors are made simply because supporters don’t understand the process of a ballot initiative.

But that doesn't always mean those signatures should be tossed.

“There’s not a huge level of knowledge about this among the voting public,” said New Approach campaign manager John Payne, who testified Monday that backers estimate more than 2,000 signatures were not counted but should have been.