§ discipline

No acting against a former client client

The lawyer must not act against a former (or another current) client where they hold that client's materially relevant confidential information, absent effective information barriers or informed consent.

26 cases 38% strike-off avg suspension 2.0 mo 9 with dishonesty finding

How the codes express this duty

E&W Solicitors SRA Principles & Code CCS 6.5 strong 22 cases
6.5 You do not act for a client in a matter where that client has an interest adverse to the interest of another current or former client of you or your business or employer, for whom you or your business or employer holds confidential information which is material to that matter, unless: ...

SRA Code of Conduct for Solicitors, RELs and RFLs · 2019 · archived copy · official source ↗

E&W Barristers BSB Handbook rC21.3; rC21.4 strong
rC21 ... .3 there is a conflict of interest, or real risk of conflict of interest, between the prospective client and one or more of your former or existing clients in respect of the particular matter unless all of the clients who have an interest in the particular matter give their informed consent ...; or .4 there is a real risk that information confidential to another former or existing client ... may be relevant to the matter ...

BSB Handbook · current · archived copy · official source ↗

Cayman Islands Legal Services Code 2026 R.7.7 strong
An attorney-at-law or a recognised law entity may act for the adversary or counterparty (client A) of a client (including a former client, client B) provided that the attorney-at-law or recognised law entity — (a) is not privy to confidential information in respect of client B that is materially relevant to such dispute or matter; or (b) can protect such confidential information effectively by the use of safeguards

Cayman Islands Legal Services Code of Professional Conduct · 2026 · archived copy

AU Solicitors Solicitors' Conduct Rules Rules 10.1; 10.2 strong 1 case
10.1 A solicitor and law practice must avoid conflicts between the duties owed to current and former clients. 10.2 A solicitor or law practice who or which is in possession of information which is confidential to a former client... must not act for the current client in that matter UNLESS: 10.2.1 the former client has given informed consent...; or 10.2.2 an effective information barrier has been established.

Australian Solicitors' Conduct Rules · 2015 (June 2026 compilation) · archived copy · official source ↗

AU Barristers Uniform Barristers Rules rr95(a),97 strong
A barrister must refuse to accept or retain a brief or instructions to appear before a court if: (a) the barrister has information which is confidential to any other person in the case ... [and] the information may, as a real possibility, be material to the prospective client's case; and ... the person entitled to the confidentiality has not consented. ... A barrister must refuse a brief to advise if the barrister has information which is confidential to any person with different interests.

Legal Profession Uniform Conduct (Barristers) Rules · 2015 (as amended 14 May 2025) · archived copy · official source ↗

IE Solicitors Law Society Guide Ch3 — Non-conveyancing transactions (prior solicitor/client relationship) partial
If the solicitor is in possession of information, gained within the prior solicitor/client relationship, that could create an unfair advantage or the perception of unfair advantage over the position of the other party, then the solicitor should consider, at the outset, whether it is appropriate to act.

Solicitor's Guide to Professional Conduct (Law Society of Ireland) · 4th ed. (2022) · archived copy · official source ↗

IE Barristers Bar Code of Conduct Rule 3.11 strong
Barristers ought not to accept instructions if they would be embarrassed in the discharge of their duties because they have previously advised on or drawn pleadings for another client on the same matter ... or they are in possession of material information entrusted to them by another client and it would be prejudicial to that client's interests ... and where they have accepted such instructions they should not continue to act.

Code of Conduct for the Bar of Ireland · 2024 · archived copy · official source ↗

JM Attorneys Canons of Professional Ethics Canon IV(t)(ii) partial 1 case
An Attorney shall not knowingly- ... (ii) use a confidence or secret of his client- (1) to the client's disadvantage; or (2) to his own advantage; or (3) to the advantage of any other person unless in any case it is done with the consent of the client after full disclosure.

Legal Profession (Canons of Professional Ethics) Rules · 1978 (principal) · archived copy · official source ↗

JE Lawyers Law Society of Jersey Code R.6.7 strong
A member or their firm may act for the adversary or counterparty (client A) of a client (including a former client, client B) provided that such member or firm is not privy to confidential information in respect of client B that is materially relevant to such dispute or matter, or can protect such confidential information effectively by the use of safeguards.

Law Society of Jersey Code of Conduct · 1 January 2017 · archived copy · official source ↗

ON Lawyers LSO Rules of Prof. Conduct r 3.4-10 strong
Unless the former client consents, a lawyer shall not act against a former client in (a) the same matter, (b) any related matter, or (c) save as provided by rule 3.4-11, any other matter if the lawyer has relevant confidential information arising from the representation of the former client that may prejudice that client.

Law Society of Ontario — Rules of Professional Conduct · current · archived copy · official source ↗

BC Lawyers BC Code r 3.4-10 strong 1 case
Unless the former client consents, a lawyer must not act against a former client in: (a) the same matter, (b) any related matter, or (c) any other matter, if the lawyer has relevant confidential information arising from the representation of the former client that may reasonably affect the former client.

Code of Professional Conduct for British Columbia (BC Code) · 2017 · archived copy · official source ↗

NZ Lawyers Conduct & Client Care Rules r 8.7.1 strong
A lawyer must not act for a client against a former client of the lawyer or of any other member of the lawyer's practice where— (a) the practice or a lawyer in the practice holds information confidential to the former client; and (b) disclosure of the confidential information would be likely to affect the interests of the former client adversely; and (c) there is a more than negligible risk of disclosure ...

Lawyers and Conveyancers Act (Lawyers: Conduct and Client Care) Rules 2008 · SR 2008/214 · archived copy · official source ↗

SCO Solicitors LSS Standards of Conduct B1.7 partial 1 case
You must not act for two or more clients in matters where there is a conflict of interest between the clients or for any client where there is a conflict between the interest of the client and your interest or that of your practice unit.

Law Society of Scotland — Practice Rules 2011, Rule B1 (Standards of Conduct) · 2011 · archived copy · official source ↗

SG Lawyers Professional Conduct Rules 2015 r 21 (Conflict, or potential conflict, between interests of current client and former client) strong
21 Conflict, or potential conflict, between interests of current client and former client

Legal Profession (Professional Conduct) Rules 2015 · 2015 · archived copy · official source ↗

HK Solicitors Solicitors' Guide Principle 9.03 strong
If a solicitor or his firm has acquired relevant confidential information or knowledge concerning an existing or former client during the course of acting for him, he must not accept instructions where it is likely that he would be duty bound to disclose or use such relevant confidential information or knowledge in breach of his duty of confidentiality to such client.

Hong Kong Solicitors' Guide to Professional Conduct (Volume 1) · current · archived copy · official source ↗

HK Barristers Bar Code of Conduct para 6.2(h) strong
if he has material information which was entrusted to him in confidence by or on behalf of another client or former client or there is a significant risk that information confidential to another client or former client might be communicated to or used for the benefit of anyone other than that client or former client without their consent;

Code of Conduct of the Bar of the Hong Kong SAR · 2018 · archived copy · official source ↗

Cases dealing with this duty

Clear

26 decisions · link basis: found breached = a tribunal finding; rule cited = the mapped provision is cited in the decision; text match = high-precision text pattern

Duty classification does not yet cover every jurisdiction (Ontario, New Zealand and Singapore decisions are indexed but not yet duty-classified), so counts here understate those corpora.