Judge Ian Thornhill ordered Linn County Auditor Joel Miller (D) to notify the affected voters in writing that their absentee ballot requests cannot be processed because they should not have been pre-filled with their personal information. The impacted voters would have to fill out new requests or vote in person on Election Day. Miller said he would comply with the order and send new blank forms to the voters in September.
The Trump campaign filed similar challenges to other counties in Iowa.
The Democrats and Republicans are waging an extensive legal battle across the nation that will shape the rules of the 2020 election. Democratic presidential nominee Joe Biden has said that his campaign has retained more than 600 lawyers for the effort.
Democrats called Thornhill's decision an act of voter suppression. Republicans said the ruling would enhance voting security and hold a "rogue auditor" accountable.