The Texas Democratic Party had challenged the state's age restrictions on voting by mail, arguing they violated the 26th Amendment's protections against voting restrictions that discriminate based on age.
Disabled and older voters have encountered the most problems navigating mail-in balloting as they try to avoid going to polling places. In-person voting has been generally smooth so far in the low-turnout runoffs.
The high court declined to immediately reinstate a federal judge's order that would have allowed all Texans to request absentee ballots if they fear catching COVID-19 at crowded polling places.
The appellate panel extended a temporary order it had issued earlier halting a federal judge's order expanding voting by mail during the coronavirus pandemic.