Mo. Rev. Stat. § 108.330
Upon hearing, whether an answer has been filed or not, the court shall carefully investigate the record concerning such bond issue, together with all evidence and proofs submitted at such hearing, and if the court be of the opinion that said bonds are legal and that the laws of the state have been fully complied with, then such court shall make an order and decree adjudging such bonds to be a valid and binding obligation upon such state, county, township, school district or municipality issuing the same; which said decree, if not appealed therefrom, shall be final, conclusive and binding upon the state, subdivision or municipality issuing the same, and the legality of such bond when so issued shall not thereafter be subject to being questioned by any other court, and the holder thereof shall be conclusively deemed to be a holder in due course, for values and without notice of defect or infirmity.
§ 108.330, RSMo
RSMo 1939 § 3314