This is a great, and I think pretty even handed, article by Bloomberg on litigating LTD claims under ERISA. Although the headline and the central thrust of the article are about obtaining LTD benefits for claims of long Covid, the article really does a nice job of explaining the entire LTD claim process and the

The Department of Labor’s regulation governing ERISA claims and administrative appeals provides a comprehensive structure for the claim process required of all ERISA plans. While there is plenty of room within the context of the regulation for a particular plan to contain its own essentially bespoke claims process, the regulation imposes the broader outline with