Colorado statutes provided that the Board of Public Works, after notice and opportunity to be heard, could order the paving of a street on petition of a majority of the owners of the property fronting thereon. Before taking effect, such an order had to be approved and implemented through adoption by the Denver City Council. After completion of the work, the Board was to determine the total cost and then make an assessment on each property fronting that street. This assessment was again required to be approved by the City Council with notice and opportunity to be heard. Londoner (P) disapproved of his assessment because a petition by the majority of the affected property owners had not been filed and the council had not afforded a hearing on that issue, and the paving had not been completed, the apportionment of costs was not proper, and the hearing procedures afforded by the Council with respect to the assessment were inadequate. The Colorado courts rejected P's challenge as the law stated that the improvement and assessment orders should be conclusive and binding on the Colorado courts. The Supreme Court granted certiorari.