Mo. Rev. Stat. § 523.261
Solely with regard to condemnation actions pursuant to the authority granted by Section 21, Article VI, Constitution of Missouri and laws enacted pursuant thereto, any legislative determination that an area is blighted, substandard, or unsanitary shall not be arbitrary or capricious or induced by fraud, collusion, or bad faith and shall be supported by substantial evidence. A condemning authority or the affected property owner may seek a determination as to whether these standards have been met by a court of competent jurisdiction in any condemnation action filed to acquire the owner's property or in an action seeking a declaratory judgment. Upon the filing of such a declaratory judgment or when such a defense is raised in a condemnation proceeding, the circuit court shall give the case preference in the order of hearing to all other cases, except elections cases, to the extent necessary to conclude the case within thirty days of having been filed. Either party may thereafter file an interlocutory appeal of the circuit court's order upholding or rejecting the legislative body's determination. Any subsequent or interlocutory appeal to a higher court on the appeal of the legislative determination shall be given preference and concluded in an expedited manner similar to the manner set forth herein for a hearing in circuit court. An interlocutory appeal shall not stay proceedings in the court unless the court of appeals so orders.
§ 523.261, RSMo