An appellate court that stopped a trial set for Monday—after Michaels Stores Inc. argued that a Houston judge sanctioned it too harshly for spoiling evidence—is now hearing the other side, which aims to block the retailer’s appeal.

The 14th Court of Appeals had stayed the trial to give Michaels more time to argue that 157th District Judge Tanya Garrison committed an error by punishing the company for failing to keep an allegedly broken shopping cart that fell over and injured a 3-year-old girl, and by deleting surveillance video just 30 days after the incident.