William Ruto and Sang, who face crimes against humanity charges over the 2007/8 post-poll chaos, will orally argue for the termination of their cases from Tuesday to Friday.
Ruto is seeking an acquittal without having to mount a defence – a laborious process that would likely distract his focus on the 2017 presidential contest.
The oral arguments are meant to strengthen his 95-page written submissions in which he accuses Prosecutor Fatou Bensouda of seeking to nail him on a “case built almost entirely on hearsay”.
He insists Bensouda’s case is based on unreliable witnesses, poor investigations and irrational conclusions.
Ruto left on Monday morning aboard Kenya Airways flight KQ116.
More than 40 MPs, led by National Assembly Majority leader Aden Duale and the Senate’s Kindiki Kithure saw him off at the JKIA.