An appeals court Texas launched in September to hear complex business matters and litigation involving the state instead is opening its doors to every type of civil case.

The legislation creating the Court of Appeals, Fifteenth District, gives an appealing party the choice of filing a case there or in the district associated with the trial court that decided the matter, the justices concluded in a stunning, split decision last month.

The development threatens to overwhelm the three-justice court, disrupt its intended purpose, and potentially bless state-level judge shopping to the all-Republican court based in Austin.

Two other appeals courts …