40 ILCS 5/18-126

Retirement annuity for permanent disability-determination of disability. A participant shall be considered permanently disabled only if (1) disability occurs while in employment as a judge and is of such a nature as to prevent the participant from reasonably performing the duties of his or her office at the time, and (2) the board has received a written certificate by at least 2 licensed and practicing physicians appointed by it stating that the participant is disabled and that the disability is likely to be permanent.