That press conference came almost six years after Mr Odinga opposed the appointment of Prof Muigai by President Mwai Kibaki.
Mr Odinga later supported Prof Muigai who took office on August 23, 2011.
On December 7, 2017, Attorney-General Githu Muigai, who resigned Tuesday, called a press conference at his State Law Office next to Harambee House.
He walked into the mid-morning briefing accompanied by Government Spokesman Eric Kiraithe.
The main news item that week was the planned protest swearing-in of opposition leaders Raila Odinga and Kalonzo Musyoka as the “people’s president and deputy” respectively.
“A swearing-in of any person ... any person who has not been lawfully declared to have won an election by the Independent Electoral and Boundaries Commission, and a swearing-in that is not conducted by the Chief Justice ... is a process unanticipated by the Constitution, and is null and void, and illegal ab initio,” Prof Muigai said.
The AG added that it was high treason for the person taking such an oath and those facilitating it.
“What is the punishment for high treason?” the bespectacled law professor asked.
“It is death,” he said with a matter of finality and after taking one of his characteristic pauses.