Conflicts of Interest
The accused's right to counsel of choice is limited by the requirement that there be no disqualifying conflict of interest. The standard require to limit the right to counsel is a high one as "a litigant should not be deprived of his or her choice of counsel without good cause".
The mischief addressed by the rules of conflict of interest are to prevent the disclosure of confidential information of previous related parties and to prevent counsel from putting himself in a situation where loyalty may be conflicted between present and past parties.
Timing of Raising Issue
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” of the accused; and
- the accused has been “denied the right to make full answer and defence” and “a miscarriage of justice has occurred.”
The test for a "disqualifying conflict of interest" has been alternatively stated as requiring:
- Did the lawyer receive information attributable to a solicitor and client relationship, relevant to the matter at hand; and
- Is there a risk that it could be used to prejudice the client?
Where it is shown that a lawyer had previously been retained on a related matter, the onus shifts to the lawyer "to prove that no information was provided that could be relevant." The test is what "would a reasonably informed member of the public be satisfied that the new retainer will not give rise to a conflict of interest".
The court must consider the public interest including the public's confidence in the administration of justice. The confidence is undermined by the appearance of an unfair trial such as a cross examination based on information obtained from prior involvement with the witness.
The court must also consider the lawyer's "duty of loyalty" as well as confidentiality and privilege.
The applicant does not need to establish that the verdict would have been different but for the conflict. 
A procedure suggested to consider conflicts goes as follows:
- It is clear that the courts have inherent jurisdiction to remove from the record solicitors who have a conflict of interest, in the exercise of the court’s supervisory authority over members of the bar; 
- The courts must be concerned not only with actual conflicts but also with perceived or potential conflicts that develop as a trial unfolds;
- The test must be such that the public, represented by the reasonably informed person, must be satisfied that no use of confidential information would occur;
- Litigants ought not to be lightly deprived of their chosen counsel, without good cause or for compelling reasons;
- A potential disqualifying conflict of interest must first be established before it can be weighed against the fundamental right to the accused’s choice of counsel;
- Typically, these cases require two questions to be answered:
- Did the lawyer receive confidential information attributable to a solicitor and client relationship relevant to the matter at hand? and
- Is there a risk that it will be used to the prejudice of the client? Consideration of these two questions is case-specific.
- Disqualification of trial defence counsel can be disruptive, and it may require a trial be adjourned in order to allow new counsel to bring themselves “up to speed”.
The courts should balance the accused's right to counsel of choice, public policy, the interest in the administration of justice and fairness.
A judge may not direct that counsel not act on behalf of the accused unless there is a "realistic risk of a conflict of interests".
The court may need to speculate on what risks may arise at trial that could cause a conflict.
Consequence of Forced Withdraw
Requiring counsel to withdraw is not a disciplinary matter, it is preventative to protect the administration of justice and ensure trial fairness.
Accused's Choice of Conflicted Counsel
The right to choice of counsel is not an absolute right.
The accused has not right to counsel who is in conflict.
Effect of Codes of Conduct
The courts are not obliged to enforce codes of conduct. The codes are only statements of public policy.
Duty to Previous Clients
The main duty Counsel as to previous clients is the duty not to misuse confidential information.
There was no conflict where defence counsel was present at the party where an assault occurred.
R v McCall, 2013 ONSC 4157 (CanLII) at para 24
R v McCallen, 1999 CanLII 3685 (ON CA) at paras 68-72
R v Billy, 2009 CanLII 63957 (ON SC),  O.J. No. 4737 (SCJ) at para 19
- MacDonald Estate v Martin, 1990 CanLII 32 (SCC),  3 SCR 1235
- R v Sandhu, 2011 BCSC 1137 (CanLII)
- R v Widdifield 1995 CanLII 3505 (ON CA), (1995), 25 OR (3d) 161 at 169
- R v Sherif, 2012 ABCA 35 (CanLII)
R v McCall at para 26
- McCall at para 27
McCall at para 27
R v Widdifield
See also MacDonald Estate
McCall at para 30
R v Robillard  O.J. No. 261 (ONCA) at page 5 (*no link)
R v Brissett, 2005 CanLII 2716 (ON SC),  O.J. No. 343 at para 39 - a lawyer should not use information obtained from a former client to cross examine them on future case.
McCall at para 31
MacDonald Estate at para 41
See also R v Billy at paras 24-25
- R v Sherif at para 13 (no conflict found)
- Macdonald Estate v Martin, at p.1245
- R v Speid, 1983 CanLII 1704 (ON CA)
R v WW, 1995 CanLII 3505 (ON CA), 100 CCC (3d) 225 at p. 238
- WW, ibid.
R v Cunningham, 2010 SCC 10 (CanLII) at para 35
- R v Cocks, 2012 BCSC 1336 (CanLII), at para 10
- Robillard, supra, at para 10
- Cunningham, supra at para 38
- Canadian National Railway Co. v McKercher LLP,  2 SCR 649, 2013 SCC 39 (CanLII)
- R v Karmis, 2008 ABQB 525 (CanLII)
An irrevocable waiver of an conflict of interests by the accused, after having received independent legal advice, will usually be sufficient to permit counsel to be retained.
However, the existence of a conflict of interest without waiver will generally result in the disqualification of counsel.
A revocable waiver can also give rise to disqualification.
There is a "heavy onus" on the accused to ensure that there is no conflict when representing multiple accused is a single matter.
There is no fixed rule preventing a lawyer from representing multiple co-accused. 
When representing multiple co-accused there is always the risk of conflict. The presence of this conflict may prevent counsel from exploring plea negotiations and possibility of one counsel testifying against another, presenting evidence incriminating the co-accused, or making sentencing submissions that only mitigate for one and not the other.
A co-accused's counsel may be enjoined from switching clients and representing an accused regardless of the consent of the accused.
Counsel have an obligation to advise them to emphasize evidence that points to co-accused and exonerates them.
Duty of Loyalty
- R v Cocks 2012 BCSC 1336 (CanLII) at para 10
- Cocks at para 10
Duty of Confidentiality
Every lawyer has a duty of confidentiality to his client. This duty extends beyond the duration of the legal relationship.
Any lawyer who has obtained confidential information from a client can never act against that client.
A lawyer may act against a former client where "a reasonable member of the public who is in possession of the facts would conclude that no unauthorized disclosure of confidential information has occurred or would occur."
The rule intends to balance the three factors of:
- the need to maintain the high standards of the legal profession and the integrity of the justice system;
- the right of litigants not to be deprived of their choice of counsel without good cause; and,
- permitting reasonable mobility in the legal profession.
Where the conflicted lawyer moves to a different firm, the other lawyers in the new firm are not necessarily conflicted as well. There will only be a conflict if:
- the lawyer at the new firm received confidential information attributable to the solicitor-client relationship
- is there a risk that the confidential information could be used to prejudice the client
There is a "strong inference" that lawyers working together will share confidential information about clients. This inference is rebutted by "clear and convincing evidence that all reasonable measures have been taken to ensure that no disclosure will occur by the ‘tainted lawyer’ to the member or members of the firm who are engaged against the former client.".
- Canadian National Railway v McKercher, 2013 SCC 39 (CanLII) at para 23
R v Imperial Tobacco Canada Limited, 2013 BCSC 1963 (CanLII) at para 22
Macdonald (Estate) v Martin, 1990 CanLII 32 (SCC),  3 SCR 1235, at 1261 ("No assurances or undertakings not to use the information will avail. The lawyer cannot compartmentalize his or her mind so as to screen out has been gleaned from the client and what was acquired elsewhere.")
- Martin at p. 1263
Imperial at para 25
- Imperial at para 27
- Imperial at para 28
Martin at p. 1260
McKercher at para 24
Imperial at para 24