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Illinois State Bar Association Ethics Opinions

Free plain-English summaries of legal ethics opinions issued by the Illinois State Bar Association, with full citations and source links on every page.

389 opinions · Updated June 10, 2026
26 opinions Former Clients

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When an Illinois personal-injury lawyer is appointed under 11 U.S.C. § 327(e) as special counsel to a Chapter 13 trustee to prosecute the lawyer's former client's uninsured-motorist claim, and the former client then fires the lawyer, must the lawyer withdraw?

The opinion concludes no. Because the claim became property of the bankruptcy estate under 11 U.S.C. § 541(a), the former client's interests are not adverse to the estate under Rule 1.9(a), and the la…

October 1, 2025

Can a lawyer who used to defend a medical group sue one of its physicians for malpractice in a factually unrelated case?

Yes, but only if the new matter is not substantially related to the former representation of the group; if it is substantially related and materially adverse, Rule 1.9(a) requires the former client's …

2022

Can a firm use screening to avoid imputing one existing partner's conflict to another partner in the same firm?

No. The opinion concludes the Illinois screening rule applies only when a lawyer becomes newly associated with a firm; it cannot insulate existing firm members from each other's conflicts, so the conf…

2018

Can a lawyer seek child support from a father when the lawyer already won child support from the same father for a different client?

Only with informed consent. The opinion concludes the new representation is substantially related to the former one and may be materially adverse, so Rule 1.9 requires the first wife's consent and Rul…

2016

When a lawyer has represented a partnership and all its partners together and one partner sues another, may the lawyer take a side?

The lawyer has a conflict and ordinarily must withdraw from the failed common representation absent informed consent. Whether the lawyer may then represent the defending partner in the arbitration dep…

2013

Can a lawyer represent a client against a witness who is the lawyer's former client from an unrelated matter, and cross-examine that former client?

Yes to the representation, with limits on cross-examination. The opinion concludes the lawyer may represent the new client in an unrelated matter, but may cross-examine the former client only without …

2005

Can I sue my former client's trustee on behalf of a trust beneficiary I jointly represented years ago in an unrelated condemnation case?

Yes. The earlier joint representation in a condemnation case was not substantially related to the beneficiary's later breach-of-fiduciary-duty claim against the trustee, so Rule 1.9 did not bar the ne…

1998

Can a lawyer who handled a client's divorce and real estate deals later represent that client's new spouse in a divorce against her?

The opinion concluded the lawyer had a conflict under Rule 1.9: because the prior divorce and real estate work for the former client was substantially related to the new divorce involving the same pro…

1995

Can a lawyer represent new clients in the same matter as a former client when the new clients' interests line up with the former client's?

The opinion concluded that representing a client in the same or a related matter as a former client is not improper under Rule 1.9 unless the clients' interests are materially adverse; where the forme…

1994

Can one lawyer represent both the driver and a passenger of the same car in a crash case where fault is disputed?

The opinion concluded that representing both the driver and passenger of one vehicle in a contested-liability collision is a classic conflict of interest that an attorney should generally not undertak…

1994

Can a former lawyer use information from the representation, like surveillance photos, against the ex-client in a later proceeding?

The opinion concluded that under Rules 1.9 and 1.6 a lawyer may not use information relating to a former representation to the ex-client's disadvantage, whenever obtained, except to the extent necessa…

1993

Can a lawyer who used to negotiate leases for a developer now represent a tenant negotiating a lease with that same former-client developer?

The opinion concluded the lawyer may not, without the former client's consent. Lease negotiation is a substantially related matter where confidences were likely shared, so Rule 1.9 bars the new repres…

1991

Can a lawyer who won a judgment for a creditor later represent an estate when the judgment debtor is a beneficiary and the creditor garnishes the estate?

The opinion concluded the representation is restricted by Rules 1.7 and 1.9: handling the garnishment for the estate is substantially related to the prior creditor representation, so the lawyer needs …

1991

Can a lawyer who jointly represented a couple on their business and estate matters later represent one spouse in their divorce?

The opinion concluded no: dividing marital assets is materially adverse to the former joint client, the lawyer would misuse shared confidences, and the disqualification is imputed to his partners and …

November 1, 1990

Can a former judge represent a litigant in a matter the judge once ruled on, years after leaving the bench?

The opinion concluded the 1990 Rules let a former judge represent a party even on a matter he ruled on, but only if all parties consent after disclosure; representation in an unrelated matter is fine,…

November 1, 1990

Can a former village attorney sue the village over a matter he worked on, if he says the information he learned is now public?

The opinion concluded it is improper: a lawyer may not take a matter where a former client's confidences could be used against it without consent, and information stays confidential until the client c…

March 1, 1989

When a former public defender becomes a prosecutor in the same county, can the rest of the office handle his old cases if he is screened?

The opinion concluded that proper screening avoids imputing the former public defender's conflict to the whole State's Attorney's office, so other prosecutors may handle his former cases without appoi…

August 1, 1988

If a non-client buys a former client's interest in the matter a lawyer once handled, can that buyer invoke the lawyer's duties to disqualify the lawyer or claim the former client's confidences?

The opinion concluded no; a lawyer's duties of confidentiality and loyalty run to the client, not to a stranger who later succeeds to the client's substantive rights, so the successor cannot disqualif…

June 1, 1987

Does representing a police officer in a disciplinary case bar a lawyer from later defending criminal cases investigated by that department or officer?

The opinion concluded no, where the matters are unrelated and the lawyer gained no confidential information usable against the former client; a concluded one-time representation of the officer did not…

January 1, 1987

Can a lawyer who won property for a divorce client later represent that client's new spouse in a divorce that would strip away the same property?

The opinion concluded no; the lawyer should decline, because attacking the property the firm had earlier secured for the former client would injuriously affect her in the very matter the firm once han…

August 1, 1986

Can a lawyer take an unrelated case against the spouse of a former client, when the spouse was not the lawyer's client?

The opinion concluded yes; nothing bars representing a client against a former client's spouse in an unrelated matter, so long as the lawyer need not use the former client's confidences and the former…

January 1, 1986

Can a law firm that jointly represented a trade association and its members later sue the association for some members over a matter from that same representation?

The opinion concluded not without a waiver from every affected client; a firm that jointly represented a trade association and individual members may not later sue the association on some members' beh…

1983

Can a lawyer take a case against a former one-time client in a totally unrelated matter that does not involve the former client's confidences?

The opinion concluded it is not per se a conflict to represent a client adverse to a former ad hoc client in a wholly unrelated matter that does not involve the former client's confidences or secrets,…

1981

Can a lawyer oppose another lawyer's client when that other lawyer is the first lawyer's own client or former client?

The opinion concluded that representing a client against a client of Lawyer B is permissible, and needs no consent, where Lawyer A only previously represented Lawyer B in a concluded matter; but if La…

1981

Can a lawyer represent a contract purchaser seeking to amend a contract that the lawyer's firm drafted years earlier for the seller, who was then a firm client?

The opinion concluded the lawyer is vicariously disqualified, even though he joined the firm after the prior representation, unless he rebuts the presumption that firm members share a former client's …

1981

After defending a client on a traffic ticket from an accident, can another lawyer in the same firm later defend the personal-injury claim that the former client brought over the same accident?

The opinion concluded it was professionally improper, and that the firm had to withdraw, because representing a client on the traffic charge and then opposing his injury claim from the same accident w…

1980

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Legal ethics opinions from the Illinois State Bar Association interpret the rules of professional conduct for working lawyers, in response to inquiries from members and committees. They are not binding like court discipline decisions, but courts and discipline boards treat formal opinions as substantial guidance on how the rules apply. Every opinion above has a plain-English question and short answer, plus a link to the original source on the bar's site.

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