Justice Nzioka dismissed an appeal by Hussein Hassan Mustafa and Mohammed Ahmed Abdi stating, "I would have enhanced the sentence if I was requested but I would leave it as it was given".
Jowie argued that laws providing death sentences are unconstitutional because they all violate Article 26(1) of the Constitution on protection of the right to life.
No executions have taken place since 1987, when Hezekiah Ochuka and Pancras Oteyo Okumu were executed for their role in the failed attempt to overthrow President Daniel Arap Moi in 1982.
His sentence remains in force unless the Court of Appeal sets aside the judgement handed by Lady Justice Grace Nzioka on Wednesday.