The ruling, delivered on Monday, 21 October, is a major setback for Mornah, who had hoped the court would reinstate him on the ballot for the 7 December polls.
Mornah's disqualification stemmed from concerns raised by the Electoral Commission (EC) over the sufficiency of his nomination forms.
Despite his argument that the disqualification was unjust, the court sided with the EC, ruling that the decision was lawful.
The presiding judge, Justice Apietu, made no order as to costs, citing the constitutional nature of the case.