The charges date as far back as the 1970s when Ralph Rowe was a minister and a Boy Scout master in several remote First Nations communities in northern Ontario.
The trial, which is by judge alone, revolves around allegations regarding acts alleged to have taken place with boys aged six to 16.
Rowe, now 66 and living in Surrey, B.C., is pleading guilty to several of the charges against him and not guilty to others.
Five men who say they were abused by Rowe will testify at the trial while about 20 others are expected to give victim impact statements.
In 1994, Rowe was convicted on 27 counts of indecent assault and one count of common assault after he pled guilty to sexually abusing 16 boys during the same time period, and in many of the same communities.
He served three years of a six-year sentence in prison for those convictions.