Canadian Criminal Procedure and Practice/Role of the Crown and Defence
Role of the Crown
The Crown Attorney is invested with the authority to conduct prosecutions on behalf of the Director of Public Prosecutions for the province or Federal government.
BC: Crown Counsel Act, RSBC 1996, c 87
MB: Crown Attorneys Act, CCSM c C330
ONT: Crown Attorneys Act, RSO 1990, c C.49
QC: An Act respecting the director of Criminal and Penal Prosecutions, RSQ, c D-9.1.1
NB: An Act Respecting the Role of the Attorney General, RSNB 2011, c 116
NS: Public Prosecutions Act, SNS 1990, c 21
FED: Director of Public Prosecutions Act, SC 2006, c 9, s 121
Purpose of Prosecution
The role of the crown is not to secure convictions, it's role is to present to a trier of fact evidence that is considered credible and relevant to the alleged offence. It is to "promote the cause of justice" and not to persuade a trier of fact "to convict other than by reason". The Crown's job includes seeking the truth. However, it does not mean seeking justice for a complainant.
The Crown is expected to "present, fully and diligently, all the material facts that have evidentiary value, as well as all the proper inferences that may reasonably be drawn from those facts." The use of rhetorical techniques to distort the evidence or to present misleading and highly prejudicial statements are inappropriate.
The prosecution of offences is not a contest between the crown and the accused. It is an investigation to determine the truth. It should be done without any feelings of animus.
The decision to prosecute is solely in the authority of the crown and should only be reviewable in the clearest of cases.
It is not necessary for the Crown to personally believe in a person's guilt to proceed on charges.
It is possible for the Crown to avoid a subpoena to provide evidence justifying the basis for exercising their discretion, such as in a corner's inquest. However, a subpoena to attend a commission inquiry to explain their actions will be enforceable.
The Crown's advice on the form charges cannot be reviewable except as a possible abuse of process.
- R. v. Boucher,  1954 CanLII 3, S.C.R. 16, 110 C.C.C. 263 at para 26
- R. v. Proctor 1992 CanLII 2763 (MB CA), (1992) 69 C.C.C. (3d) 436 at para 59 and adopted in R v Trochym 2007 SCC 6
- R v Trochym 2007 SCC 6
- R v Trochym 2007 SCC 6 at 79
- R. v. Chamandy (1934), 61 C.C.C. 224, at p.227
- Miazga v. Kvello Estate, 2009 SCC 51
- Miazga v. Kvello Estate, 2009 SCC 51 at 65 to 67
- Picha v. Dolan, 2009 BCCA 336
- Attorney General v. Davies, 2009 BCCA 337
- R. v. Ghavami, 2010 BCCA 126
Discretion of Crown
The prosecution is empowered with discretionary authority over many decisions that have limited ability to be reviewed.
Core matters of prosecutorial discretion cannot be reviewed except for abuse of process.
Matters that have been found to be part of the core function of the Crown and so subject to prosecutorial discretion include:
- the decision to prosecute
- the stay of a charge
- the withdrawal of a charge
- the acceptance of a lesser charge
- the Crown election
- taking control of a private prosecution
- the decision to appeal
- the decision to consent to an adjournment 
- consenting or refusal to consent to re-election
- notice to seek increased penalty
- R. v. D.N., 2004 NLCA 44 (CanLII) at para. 17
Krieger v. Law Society of Alberta, 2002 SCC 65 (CanLII),  3 SCR 372
R. v. Power, 1994 CanLII 126 (SCC),  1 SCR 601 at para. 41 to 43
- D.N. and R v Beare 1988 CanLII 126 (SCC),  2 SCR 387 at para. 51
- R. v. Ng, 2003 ABCA 1 (CanLII)
- R. v. Gill, 2012 ONCA 607 (CanLII)
Relationship with Police
The Crown and police are to consult with each other but the "maintenance of a distinct line between these two functions is essential to the proper administration of justice."
The Crown can be liable for their part in giving advice to police during an investigation.
While it is acceptable, the Crown should not try to be involved in interviews with parties prior to charges being laid.<reff> R. v. Regan, 2002 SCC 12,  1 SCR 297 at 61-70</ref>
To establish malicious prosecution the plaintiff must prove the following:
- Initiated by the defendant;
- Terminated in favour of the plaintiff;
- Undertaking without reasonable and probable cause; and
- Motivated by malice or a primary purpose other than carrying the law into effect.
The crown must remain separate from the police. 
Judge shopping is where counsel attempts to influence which judge will hear a particular matter. Judge shopping by crown counsel is not acceptable as it suggests that the system is partial.
R. v. Scott,  3 SCR 979
R. v. Regan, 2002 SCC 12,  1 SCR 297 at 61
R v Pilarinos 2001 BCSC 1690
Agreements made by a Crown Attorney is binding upon the Attorney General. Their word is to be relied upon. Thus, if a subsequent Crown were to repudiate an agreement could be an abuse of process. 
- Aucoin v. Nova Scotia (Attorney General) (1990) 94 N.S.R. (2d) 205 -- first crown agrees to withdraw charges, attorney general directs charges to proceed
R. v. Hardick  N.S.J. No. 305 - charges stayed
Role of the Defence
A lawyer representing an accused must have undivided loyalty to their client. Loyalty is a fundamental principle of the solicitor-client relationship and is essential to the integrity of system and the public's confidence in it.
This requires that there be no conflict of interest with the lawyer. A conflict of interest is where there is "a substantial risk that the lawyer’s representation of the client would be materially and adversely affected by the lawyer’s own interests or by the lawyer’s duties to another current client, a former client, or third person."
- R. v. M.Q., 2012 ONCA 224 at 26
- see R. v. Widdifield 1995 CanLII 3505 (ON CA), (1996), 25 O.R. (3d) 161 (C.A.), at pp. 171-172.
- R. v. Neil, 2002 SCC 70 (CanLII), 2002 SCC 70,  3 S.C.R. 631, at para. 31
Conflict of Interest
Issues of conflict of interest of trial counsel can be raised at any point including on appeal after trial. 
The party alleging the conflict must demonstrate that:
- an actual conflict of interest exists
- there is “some impairment of counsel’s ability to represent effectively the interests” fo the accused
- the accused has been “denied the right to make full answer and defence” and “a miscarriage of justice has occurred.”
The applicant does not need to establish that he verdict would have been different but for the conflict. 
A co-accused's counsel may be enjoined from switching clients and representing an accused regardless of the consent of the accused.
- R. v. Quiriconi, 2011 BCSC 1737