The New York State Insurance Department must submit for court review e-mails sent between its former commissioner, Eric Dinallo, and four of his top aides as it defends a lawsuit brought by 18 banks claiming $5 billion in damages from the department’s decision to let the giant bond insurer, MBIA, reorganize, an appellate judge in Manhattan ruled yesterday.

In November, then-Justice James A. Yates ordered MBIA to submit any e-mails related to the reorganization for review by a judicial hearing officer to determine whether they contain evidence that they disregarded their “pure statutory obligation” to review MBIA’s application to reorganize “fairly for all the policyholders of MBIA.”