Defendant instituted a policy requiring public housing tenants to post a $180 deposit to commence water service whereas all others needed only a $55 deposit.  Plaintiff sued, claiming disparate impact discrimination in housing.  To make a prima facie case on that claim, plaintiffs had to (1) the existence of a policy, not a one-time decision, that is outwardly neutral; (2) a significant, adverse, and disproportionate effect on a protected class, of which the plaintiff is a member; and (3) robust causality that shows, beyond mere evidence of a statistical disparity, that the challenged policy, and not some other factor or policy, caused the disproportionate effect.  Plaintiff demonstrated those elements.  The higher deposits required of public housing tenants was a policy which did not expressly discriminate on protected status.  It had a disproportionate effect on minorities as they constituted far higher percentages of public housing tenants than percent of the general population served by defendant.  And, the policy clearly caused that disproportionate impact.  However, defendant established it had a valid business reason for the policy–the public housing authority refused to pay when its tenants left outstanding water bills in excess of their deposits.  Plaintiff did not suggest any alternative measure that would serve defendant’s business interest as well without disparate impact.