Legal Question in Disability Law in Illinois

A psychiatrist can certify someone incompetent after an evaluation.

If a trust is involved, sometimes it will define the term in the context of such person acting as trustee.

Otherwise, a case must be opened in the guardianship (usually the probate division) court of the county where the person resides, and there will be a competency hearing to determine the person's status.

There may be other ways, depending on the situation and the documents involved. Either way, you should seek the advice of counsel who can make a determination based on all of the facts.

Good luck to you.