The ECCC is powerless to consider an alleged misconduct of a national judge

In the Nuon et al. case (Extraordinary Chambers in the Courts of Cambodia), the Defence sought the disqualification of the Trial Chamber's President on the basis of alleged misconduct during his tenure as the President of one of the Cambodian provincial courts.
The Defence alleged that prior to joining ECCC, the judge admitted that he had “accepted cash gratuities from grateful litigants.”

The Trial Chamber dismissed the motion and held that, where allegations concern the fitness of an individual to serve as a judge, the relevant mechanisms within the ECCC context are the domestic mechanisms designed to uphold standards of judicial integrity within the Cambodian judiciary.

Nuon et al., Decision on Ieng Sary's Application to Disqualify Judge Nil Nonn and Related Requests, Case No. 002-ECCC, T. Ch., 28 January 2011