LEASE — public housing — rental rebates — statutory right of termination — lease terminated — cancellation of rental rebates — backdating of cancellation — recovery of past rebates and subsidies — recovery of rent — recovery of occupation fee — decision of Civil and Administrative Tribunal — issue estoppel — whether necessary and fundamental finding of fact — whether actually decided — whether within general jurisdiction of Tribunal — whether special circumstances — collateral review on administrative decision — ambit of collateral attack — jurisdiction of District Court — statutory rebates permitted — retrospective cancellation permitted — whether retrospectivity extends to rebates prior to enactment — whether pre-enactment rebates were taken to be granted under enactment — statutory basis for grant of rebate — transitional provisions — was rebate in force immediately before enactment — what was “corresponding provision” — effect of purported cancellation of earlier subsidies — whether decision made by the Corporation — identity of decision maker — authority of decision maker — delegation — agency — discretion to requirement repayment — prior investigation into weekly income — decision to recover more than amount permitted — correct amount of rebate recoverable — effect of error on decision — whether claim statute-barred — date cause of action arose — whether notice of increased rent required — date of vacant possession
