KVSS immunity protects Modvat credit settlements from reopening despite statutory validation of denial of HSD credit. The issue concerns whether Modvat credit on High Speed Diesel, finally determined under the Kar Vivad Samadhan Scheme, is recoverable after a statutory provision validating denial of such credit; the Chief Commissioner held that KVSS immunity is statutory (not a judicial order) and therefore not reopened by the validating provision, and the Board concurred, directing field formations to treat KVSS settled Modvat cases as protected from recovery.