Handler's noteworthy achievement is a case considered to be a landmark case that was won on an ironic, yet relatively simple, but critical oversight. At issue were the sale of intellectual property rights to certain Marvel Enterprises characters that Marvel's new owners thought it bought with the company. The claim was successful because, although the purchaser of those rights had a valid signed contract with the former owners of Marvel, the actual new rights were never registered with the United States Copyright Office. Handler's discovery of that fact, and her interpretation of IP law during the court proceedings, caused the rights to revert to Marvel, which was bought by Avi Arad and Ike Perlmutter.