What are the rights of the citizen against child protective services?

My sister is on methadone... she got pregnant and is quitting it as fast as she can, she's down to 16mgs now, but can't just quit because that would cause fetal distress and miscarriage. She has a lovely child on scholarship in private school where people simply do NOT have CPS cases, and if they came to the school, she would have to switch her child to another school to avoid the shame of it all and the stigmas against her child. She hopes to have the meth out of her system by the time the baby is born, but if she doesn't, does CPS always have to be called? Can you get a lawyer to keep them from nosing in your life and ruining your reputation in the community? Not to mention the hideous thought of foster care, where her children would NEVER get the opportunities she can provide them, plus the prominance of abusive foster parents/ones who take in kids to collect a welfare check. Even the allegation of neglect, abuse, or whatever is enough to ruin a family, and CPS NEVER apologizes