Justices Aggrey Muchelule, Gatembu Kairu, and Weldon Korir rejected a request from Masengeli's legal team, led by Cecil Miller and State Counsel Emmanuel Bitta, to temporarily halt the sentence pending the appeal.
Law Society of Kenya (LSK) pleaded with the Court to be granted a day to file further submissions in response to Masengeli's application.
Justice Lawrence Mugambi sentenced Masengeli after defying summons seven times in relation to the disappearance of Bob Njagi, Aslam Longton, and Jamil Longton, who were abducted in Kitengela two months ago, by people who identified themselves as police officers.
The Law Society of Kenya (LSK), pundits and civil society groups want Masengeli held personally responsible for his refusal to obey the seven court orders, accusing him of being "a criminal and fugitive" unfit to hold public office under the 2010 Constitution.
Speaking to The Standard, LSK President Faith Odhiambo condemned Masengeli’s defiance, noting that it sets a dangerous precedent for police officers who are by law enforcers of the rule of law - should uphold it at all times.
"The court has jurisdiction over the Acting IG, and there are other constitutional avenues we will consider," Odhiambo said. "The LSK’s role is to uphold and defend the rule of law."