With approximately 80 million Americans projected to vote by mail in November, parties have turned to the courts to clarify the appropriate ways to adapt, apply, and administer the rules of mail voting for pandemic elections. Plaintiffs across the country have filed more than 200 cases and appeals challenging nearly every aspect of the absentee balloting process, asserting claims under a variety of state and federal laws. This report outlines the many legal challenges to absentee and mail voting systems brought since March, largely in response to the COVID-19 pandemic.