Is "disparate impact" really a problem?

Powerline discusses an important--maybe--case before the Supreme Court where the Court is being asked to establish whether the criteria of "disparate impact" applies to housing.   They define it as when a policy excludes or injures a group without a legitimate interest, and give the examples of school disciplinary standards or employment standards (say for police or firefighting work) as examples where this standard has done harm.

But that said, any parent can tell you that relaxing disciplinary standards in school is guaranteed to cause problems where good students aren't allowed to learn.  Relaxing standards for police or firefighting work guarantees that crimes do not get solved and fires don't get put out readily. 

In other words, I'm at a loss to think of cases where the disparate impact criteria are met--you will find plenty of places where one minority is harmed, but not too many of them are cases where there is no legitimate reason to do so. 

So what's the problem, then?  The problem, as far as I can tell, lies in attorneys general (state and federal level) who use the tool to intimidate school districts, police departments, and the like into doing their will.  It is a legal blackmail tool. 

And so if it's happening in your area, there are two things to be done.  One can either repeal disparate impact laws, or alternatively simply rein in the attorneys general who mis-use it and encourage the victims to point out that yes, there is a very real reason for the policies in question.