In a merger review, the Commissioner of Competition has the
power to issue supplementary information requests
("SIRs") to merging parties, in addition to the standard
disclosure required under the Competition Act. The authors suggest
that the principle of proportionality is and should be applicable
to the exercise of the Commissioner's SIR power; however,
current merger review procedures, including pre- and post-issuance
dialogue and the Competition Bureau's internal appeal process,
do not provide effective avenues for parties to challenge the scope
or proportionality of a SIR. Recent decisions of the Competition
Tribunal suggest that the principle of proportionality—well
recognized in civil proceedings in Canada—is equally
applicable in Tribunal proceedings. If a party were to take the
risky course of closing a transaction over the Commissioner's
objections after refusing to comply with an overbroad SIR, and in
the event of a proceeding brought by the Commissioner,
