I don't understand why Michael couldn't sue Captain McCluskey for striking him outside of the hospital. I mean, Michael had plenty of witnesses to testify against McCluskey and could have possibly gotten McCluskey suspended from the force or something along those lines. Michael could have played the "but I'm his son" type of excuse, which would have been perfectly legitimate because Michael wasn't part of the family at that time. I know the other Families would have been furious but like Clemenza said, wouldn't they still have to recognize Michael as a "civilian"?