The judge-alone trial, which involves 31 charges including fraud, breach of trust and bribery, is set to unfold April 7 in Ottawa.
Several subpoenas have already been issued to a range of figures, including sitting senators, people who Duffy contracted for services, and Senate administrative officials.
Vaillancourt was the trial judge in 1999 who dealt with the complex issue of how to define the Metis and their constitutional rights, in a case that involved an Ontario father and son moose hunting without a license.
That case ended up going all the way to the Supreme Court of Canada.
In 2014, Vaillancourt came up with a compromise solution for a niqab-wearing woman who was the complainant in a sexual assault case.
Vaillancourt allowed only the back of her head to be shown to most of the courtroom, while the accused, Crown lawyers, court staff and the judge saw her without a veil.