Definition of Adverse Impact
Adverse impact is the negative effect that appears natural but has a biased effect on a protected group. In the US, protect group includes age (40 and above), gender, race, religion, etc. The adverse impact may happen during recruitment, promotions, layoff, training, and development or mostly during performance appraisals. This effect may occur in a whole procedure or any part of the procedure.
Managers may do this on purpose to slow down the organizational progress but they may face legal trouble in altering the process which may seem natural but hurt the protected group.