Is a parent permitted to bring an advocate or attorney to an IEP meeting?
Yes! Parents are permitted, at their own discretion, to bring to the IEP meeting any individual with "knowledge or special expertise regarding the child." 20 U.S.C. 1414(d)(1)(B)(vi); 34 C.F.R. section 300.344.
This can include an advocate, friend, relative, attorney, other professional, caseworker / social worker, therapist, etc.
It is important to note that if the parent invites the individual, it is the parent who has the ability to make the determination as to whether the person has "knowledge or special expertise." The District can't, therefore, prevent parents from bringing an advocate or an attorney to the meeting! Even if there isn't already a dispute, and even if the District has not invited their own attorney, the parent has the explicit right to include any individual he/she deems to be an appropriate IEP team member, including their attorney or advocate.
This provision goes towards the ability of parents to meaningfully participate in the IEP process. Parents can choose to bring an educational advocate or special education attorney to assist them in participating and will help to ensure that they fully understand the offer. If they are denied the right to bring such persons to an IEP meeting, they may in turn be denied the ability to give informed consent to the program.