The trust instrument refers to the actual documents that comprise the trust. The trust instrument is legally binding. It names the trustee, donor, terms of the trust, assets of the trust, beneficiaries of the trust and stipulations that are a part of the trust. The trust should also contain contingencies for trustees should the first one fail. It also must contain the signature of the grantor or person creating the trust and should be legally notarized. Trust instruments are best prepared by financial planners who know the nuances of financial law and can help select the best trust for any given situation.