Social Security beneficiaries snared in the largest disability scam in U.S. history won a reprieve last week when the government said it will put off decisions on revoking their benefits until the new year. The reversal by the Social Security Administration comes after the federal government finally took possession of and named receivers for thousands of case files from Eric C. Conn, the lawyer who orchestrated the disability-fraud ring. The files, which had been sitting in Conn’s law office for years, contain evidence that might help the beneficiaries prove they were entitled to benefits the government is now trying to...