Extradition — Rule of specialty — Accused extradited to Canada from Brazil — Canada undertaking to prosecute fugitive for crimes listed in extradition request — Immunity for crimes committed before surrender — Later charged with offences committed prior to request for extradition — Whether appellant had a reasonable opportunity to return to the requested State — Whether immunity from prosecution perpetual — Extradition Act 1970

Treaties — Interpretation — Undertaking by Canada — Whether to be read in light of its object and purpose as well as in the light of general principles of international law — Whether interpretation to involve minimum obligations for the parties and to be most favourable to the freedom and independence of States — Vienna Convention on the Law of Treaties, 1969 — The law of Canada