If a lawyer receives an opposing party's confidential documents that opposing counsel sent by mistake, can the lawyer use them?

Plain-English summary

The inquiry arose from two fact patterns. In the first, a settlement spreadsheet was faxed to opposing counsel by mistake; the receiving lawyer announced he intended to use it to enforce the settlement. In the second, a draft settlement agreement bearing a partner's note about preserving a defamation claim was faxed in error, and opposing counsel responded with a revised draft barring that claim. The inquiring lawyer asked about his duty to tell his clients, the constraints on the receiving lawyer, and his own malpractice exposure.

Surveying the conflicting authorities, the Committee adopted the approach of District of Columbia Bar Opinion No. 256 over ABA Formal Opinion 92-368. It concluded that there is no ethical prohibition against a receiving lawyer using information obtained while reviewing a document sent by opposing counsel, and that Rule 1.3 (diligence) may even require using material information; treating the information as off-limits could itself create a Rule 1.7(b) material-limitation conflict. The Committee reasoned that once confidential material has been read it cannot be purged from memory, and that ABA Formal Opinion 92-368 placed the burden on the wrong party by asking the receiving lawyer to act against their own client's interests to protect the careless lawyer.

The Committee drew a line at notice. Relying on the District of Columbia opinion, Lipin v. Bender, and the Illinois Preamble's caution that zealous representation does not mean acting unfairly or oppressively, it concluded that a lawyer who has notice of the inadvertent transmission before opening or reviewing the materials should not review or use them. On the inquiring lawyer's own side, Rule 1.4 required him to inform the affected clients of the errant transmissions so they could make informed decisions about the settlement negotiations, supported by Rule 1.6 (confidentiality) and Rule 5.3 (supervision of nonlawyer staff). The Committee declined to address the malpractice question as beyond its mission, and agreed with ABA Formal Opinion 94-382 that a lawyer should not use information obtained through deceit, illegality, or breach of trust by an opposing party's agent.

Currency note

This opinion was issued in 1999, before Illinois adopted its current Rules of Professional Conduct, effective January 1, 2010. The Illinois Rules cited here use the pre-2010 numbering, and the 2010 Rules added Rule 4.4(b) on inadvertently sent documents. The ISBA notes the opinion was affirmed by its Board of Governors in January 2010 as generally consistent with the 2010 Rules, though the specific standards referenced may differ. Treat this page as historical context, not current guidance. Verify against current rules before relying on any specific rule or requirement mentioned here.

Common questions

Q: Can a lawyer use confidential documents that opposing counsel faxed by mistake?

A: The opinion concluded that a lawyer who reviewed the materials before having any notice of the error could use the information, and that Rule 1.3 might require using it if material to the matter.

Q: What changes if the lawyer is warned about the mistake before opening the materials?

A: The Committee concluded that a lawyer who has notice of the inadvertent transmission before opening or reviewing the materials should not review or use them.

Q: Does the lawyer who sent the materials by mistake have to tell their own client?

A: Yes. The opinion concluded that Rule 1.4 required the lawyer to inform the affected clients that confidential information had been transmitted to and read by opposing counsel, so the clients could make informed decisions.

Q: Did the opinion decide whether sending the materials was malpractice?

A: No. The Committee declined to opine on potential malpractice liability, treating it as beyond the scope of its mission.

Background and rules framework

The opinion framed the question under the Illinois Rules on diligence (1.3), communication (1.4), confidentiality (1.6), conflicts (1.7(b)), safekeeping property (1.15), supervision of nonlawyers (5.3), and misconduct (8.4), corresponding to the parallel ABA Model Rules. It surveyed competing authorities, including ABA Formal Opinions 90-358, 92-368, and 94-382, District of Columbia Bar Opinion No. 256, Oregon State Bar Formal Opinion 1998-150, and the draft Restatement of the Law Governing Lawyers, before adopting the District of Columbia view.

Citations and references

Rules of Professional Conduct:

• Illinois Rules Preamble, 1.3, 1.4, 1.6, 1.7(b), 1.15, 5.3, 8.4 (Model Rules 1.3, 1.4, 1.6, 1.7, 1.15, 5.3, 8.4)

Cases:

• Lipin v. Bender, 84 N.Y.2d 562, 644 N.E.2d 1300 (1994), surreptitious use of an opponent's documents found dishonest

Other opinions cited:

• ABA Formal Opinions 90-358 (1990), 92-368 (1992), 94-382 (1994)
• District of Columbia Bar Opinion No. 256 (May 16, 1995)
• Oregon State Bar Formal Opinion No. 1998-150 (April 1998)
• ISBA Opinion No. 95-10 (1996)

See also

• ABA Ethics Op. 05-437: Inadvertent Disclosure of Confidential Materials
• ABA Ethics Op. 06-440: Unsolicited Receipt of Privileged Materials
• NYC Bar Ethics Op. 2019-3: Use of Inadvertently Received Information

Source

• Landing page: https://www.isba.org/ethics/opinions/9804