It was a psychiatric disability case and those are tricky and require a bit more attention from the disability insurer. Dr. Grimes, the reviewing psychiatrist made the decision to deny based on the opinion that the claimant was able to perform her job. She made that decision without any knowledge of the claimant's job, without interviewing the claimant, and without consulting with all of the claimant's treating mental health professionals.
That might fly in physical disability cases because often the records can speak for themselves, but when they're dealing with psychiatric disability it's important to have a physician actually meet with the claimant to determine the extent of the disability. Unfortunately that's not how the insurance companies want to do it, so they don't. Trying to save a little time and money and they're asking for litigation. Well, again, they got it. Next time they should take the time to actually review the claim and save everyone the hassle of court by accepting the initial claim.
Click here to read the full opinion of Allen v. AT&T Disability Income Program, the case in question.