In all proceedings in any court of this state, the record of any declaration, deed, or mortgage, or other muniments of right, referred to in sections 36-2-103 and 36-2-105, shall be received, except as against the United States, and all persons claiming under the United States, as presumptive evidence of the regularity of the paper itself, under the local law or custom existing at the time of its execution; and, if the regularity thereof is challenged, the burden of proving the alleged irregularity shall rest upon the party making the challenge.
C.R.S. § 36-2-106