Wanjala served as a deputy director in charge of prevention of the now defunct Kenya Anti-Corruption Commission.
[2] He resigned on 18 September 2009 due to public outcry following the irregular reappointment alongside his boss Aaron Ringera and fellow deputy director Fatuma Sichale by President Mwai Kibaki.
[5] When the first round of the presidential election took place on March 4, 2013, it resulted in the two frontrunners, Uhuru of Jubilee and Raila of CORD, clinching 50.6% and 43.7% of the vote respectively.
The highly awaited verdict, given amid great tension in the country, was rendered in favour of Uhuru Kenyatta and was unanimous.
In September 2017, he was one of four judges who voted to nullify President Uhuru Kenyatta's win in the August 2017 presidential election.