735 ILCS 5/8-1208
The official certificate of any register or receiver of any land office of the United States, to any fact or matter on record in his or her office, shall be received in evidence in any court in this State, and shall be competent to prove the fact so certified. The certificate of any such register, of the entry or purchase of any tract of land within his or her district, shall be deemed and taken to be evidence of title in the party who made such entry or purchase, or his or her legatees, heirs or assigns, and shall enable such party, his or her legatees, heirs or assigns, to recover or protect the possession of the land described in such certificate, in any eviction action or action of ejectment , unless a better legal and paramount title be exhibited for the same. The signature of such register or receiver may be proved by a certificate of the Secretary of State, under his or her seal, that such signature is genuine.
735 ILCS 5/8-1208