Toronto Police Chief Bill Blair had appointed Dennis O'Connor earlier this month to conduct the review following the streetcar shooting of 18-year-old Sammy Yatim, as well as several other fatal police shootings in recent years.
The retired justice said in a statement on Wednesday that he is withdrawing from the formal review because of his current work with a law firm that acts for the insurers of the Toronto police in civil suits.
Some of those suits also include allegations of excessive and sometimes legal forces, the statement said.
O'Connor said lawyers for some of the victims' families raised objections but neither he nor Blair considered his association with Border Ladner Gervais to have a direct bearing on any advice he would have provided.
The decision to withdraw from the review was intended to limit any distractions to the work of the review, O'Connor said.