Counsel for the defence and the state play an active role during the jury selection process in Canada by exercising a limited number of peremptory challenges.
Peremptory challenges allow counsel to exclude a prospective juror without having to provide reasons to the trial judge overseeing the selection process.
The authority for the peremptory challenge process is found in the Criminal Code of Canada. This process takes place after the judge pre-screens the group of prospective jurors for eligibility, competency, and obvious partiality.
The number of peremptory challenges available to each counsel depends upon several case-specific factors, including the maximum potential punishment for the most serious offence charged (Criminal Code s. 634).
The order in which the judge will call upon counsel to exercise peremptory challenges is addressed in s. 635 of the Criminal Code. After the court clerk randomly selects the initial prospective juror from the judicially pre-screened panel, the judge will call upon defence counsel first to indicate whether the individual is acceptable ("content") or subject to a peremptory challenge ("challenge"). If both counsel are content, the individual will become a member of the jury. The state will be called upon first for the next randomly selected individual, and the order then alternates back and forth until twelve jurors are selected.
Counsel in Canada have very limited information to draw upon when deciding whether to exercise a peremptory challenge - the jury panel list that counsel receives in advance of the trial date contains only the name, address, and occupation of each prospective juror. Furthermore, counsel are not permitted to ask questions of prospective jurors during the peremptory challenge process.
The following comments from Karatkasanis, J, speaking for a unanimous Supreme Court of Canada in R. v. Davey,  S.C.J. No. 75, at para. 32, provide additional insight into the peremptory challenge process:
...the Criminal Code gives the parties a limited opportunity to object to specific jurors chosen from the jury list. Peremptory challenges can be exercised on purely subjective grounds. Crown counsel, as local ministers of justice, exercise that choice on behalf of the public. The alternating order and equal number of peremptory challenges give both the Crown and the defence an equal opportunity to object to a limited number of potential jurors to address any other concerns regarding suitability or concerns that may fall short of proof of partiality. Our ... jury selection process ensures equality of influence over the composition of the jury as between the parties.
In addition to the peremptory challenge process, section 638 of the Criminal Code also provides for a "challenge for cause" - for example, when case specific factors (pre-trial publicity, race-based prejudices...) raise a realistic concern as to whether the panel of prospective jury members could be predisposed to decide the case in favour of the prosecution. The challenge for cause will be examined in a subsequent post.