I can only give you a generalized answer from my experiences of the past.
When people, in large quantities are breaking the law and asked to disburse, if they refuse, then the police have the duty to arrest the most violent offenders, but using on the minimal force necessary to effect the arrest.
If you are referring to the 87 year old woman that was pepper sprayed….well, she was asked to leave and she refused. Her age made no difference. Suppose she killed her grandchildren. Just because sheis 87 years old does not change the law one bit. The criminal laws do not vary that much, depending on the violation, not the age, except with a juvenile.
The police may be sued, but the bottom line is they were doing their job to protect the health and welfare of all the citizens.
I agree with occupy, but when the police tell you to move, then you should move.