Me. Stat. tit. 36 § 1083
In the trial of any civil action, involving the validity of any sale of real estate for nonpayment of taxes, it shall be sufficient for the party claiming under it, in the first instance to produce in evidence the tax collector's deed, duly executed and recorded, which shall be prima facie evidence of his title, and if the other party claims and offers evidence to show that such sale was invalid and ineffectual to convey the title, the party claiming under it shall have judgment in his favor so far as relates to said tax title, if he then produces the assessment, signed by the assessors, and their warrant to the tax collector, and proves that such tax collector complied with the requirements of law in selling such real estate. In all civil actions involving the validity of such sales the tax collector's return to the municipal clerk shall be prima facie evidence of all facts therein set forth.
36 M.R.S. § 1083