First off, don't think that you're powerless. Regardless of what the school may tell you, if your son or daughter has an IEP and has been suspended or is facing expulsion, you have a great deal of control over what happens next.
This article raises questions about 504 plans and/or IEPs: Parent Sues School District Over Service Dog For Son With Cerebral Palsy. In this case, a parent of a child with a disability is suing the school district because the district isn't allowing his child to bring in his service dog. I have yet to see anything like this in the Denver area, but it wouldn't necessarily surprise me. Many people may look at a story like this and think it's ridiculous, but it actually raises some important questions.