Changes the law regarding primary elections

HB 1156 changes Missouri's primary election rules by requiring voters to be officially affiliated with a political party to vote in that party's primary, based on their registration status as of the 23rd Tuesday before the election. The bill also restricts public access to detailed voter information (like full addresses), allowing only specific entities like candidates or parties to obtain limited data (names, addresses, party affiliation) for election purposes, with strict limits on commercial use or public internet release. It includes new protections for vulnerable individuals (e.g., domestic violence victims, undercover officers), enabling them to petition courts to close their residential addresses in voter records to prevent safety risks. Additionally, voters changing party affiliation within 23 weeks of a primary election must retain their prior affiliation for that election, with changes taking effect only after the primary.