Holding review of the Board's decision to apply a new rule of law retrospectively is deferential and that the Board's ruling will be disturbed only if it wreaks manifest injustice
In Knogo we said that among the mitigating factors the NLRB is obliged to consider before issuing a bargaining order are the passage of time and the rate of employee turnover and we held that "[a]lthough `we must guard against rewarding an employer for his own misconduct or delaying tactics,'" At 60, quoting Jamaica Towing, 632 F.2d at 214, where the company was not responsible for twenty-two months of the lapse of time and there was a large employee turnover, a bargaining order should not issue.