ABA Rule 1.6 & Client Confidentiality When You Share Files

There’s a comfortable assumption behind a lot of file-sharing: that if you were careful — you blacked out the names, you didn’t attach the wrong version — you’ve met your duty. Rule 1.6 asks for something both easier and harder than perfection. It asks for reasonable efforts. This is a plain-English look at what that means the moment a client file leaves your office, where confidential information actually slips through, and what handling it well looks like in practice.

What Rule 1.6 actually requires

Most lawyers know Rule 1.6 as the duty of confidentiality. The part that governs sharing files is subsection (c), added by the ABA’s 2012 Ethics 20/20 amendments to modernize the rule for a digital practice:²

“A lawyer shall make reasonable efforts to prevent the inadvertent or unauthorized disclosure of, or unauthorized access to, information relating to the representation of a client.” — ABA Model Rule 1.6(c)¹

Two words carry the weight. “Inadvertent” means the rule covers accidents, not just leaks you meant to make — the redaction that didn’t take, the attachment you didn’t mean to send. And “reasonable efforts” means the standard is not a guarantee. Comment [18] to the rule is explicit that a disclosure does not violate subsection (c) if the lawyer made reasonable efforts to prevent it. You are judged on the care you took, not on whether something ever slips.

Comment [18] lists the factors that decide whether your efforts were reasonable:

• the sensitivity of the information;
• the likelihood of disclosure if additional safeguards aren’t used;
• the cost of those safeguards;
• the difficulty of implementing them; and
• the extent to which a safeguard would get in the way of the representation — a tool so cumbersome no one actually uses it.¹

Read together, that’s a workmanlike standard. The more sensitive the file and the easier the leak, the more is expected of you — and a safeguard that’s cheap, easy, and unobtrusive is one you have little excuse to skip.

Where confidentiality leaks when you share files

The exposure isn’t evenly spread. It concentrates in the documents you hand off most routinely, where the sensitive data is dense and the deadline is close.

• Court exhibits and e-filings. Public and effectively permanent. A filing carries Social Security numbers, financial account numbers, birth dates, and the names of minors — the identifiers the federal privacy rule requires you to redact (down to the last four digits of an SSN or account number, a minor’s initials, the year of a birth date) before the document reaches a public docket, and that rule reaches exhibits and material filed in discovery, not just the pleading.³
• Discovery productions. Hundreds or thousands of pages going to opposing counsel. One un-redacted bank statement or medical record in the set is a disclosure, and at that volume it’s the page you didn’t look at closely that gets you.
• Medical records in a case file. Personal-injury, med-mal, and workers’-comp files are thick with protected health information. HIPAA’s Safe Harbor method names eighteen identifier types to strip for de-identification — medical record numbers, dates of birth, and provider identifiers among them.⁴ The clinical content itself, such as a diagnosis or an ICD-10 code, isn’t on that identifier list, but it is often exactly what you need to redact for confidentiality before the file travels.
• Demand packages and settlement material. Sent to insurers, adjusters, and mediators, often bundling a client’s records, wage information, and identifiers into a single PDF built under time pressure.

In every one of these, the sensitive material is specific and nameable — not “confidential information” in the abstract, but an SSN, an account number, a child’s name, a diagnosis code. That specificity is the point: it’s what you’re on the hook to find and remove.

Why the usual approaches fall short

Three habits feel like reasonable effort but leave a gap a Comment [18] analysis would notice.

• Reading the page by eye. Careful review catches the obvious. It misses the differently-formatted phone number, the SSN written without dashes, the account number in a footer — and it doesn’t scale to a thousand-page production.
• Drawing a black box over the text. The most common failure of all. A black rectangle in most PDF tools is a shape laid on top of live text — the words underneath are still in the file and come right back with a copy-paste or a text extractor. It looks redacted; it isn’t. Two decades of high-profile examples show how reliably this one backfires.
• Uploading the file to an online redaction service. Here the tool itself raises the question the rule is asking. To use most web-based redactors you first send the un-redacted client file to a third party’s servers. The ABA has been explicit that transmitting client information electronically is governed by that same reasonable-efforts standard,⁵ so the upload isn’t a neutral step — it’s a disclosure to an outside party that you would then have to be prepared to justify. You may have solved the black-box problem by creating a data-custody one.

What handling it well looks like

Map the Comment [18] factors — sensitivity high, likelihood real, cost and difficulty low — and a sensible baseline falls out.

Keep the file on your own machine. The cleanest way to prevent unauthorized access during redaction is to never hand the document to anyone to redact it. Redaction that runs entirely on your computer — nothing uploaded, nothing sent to an outside service or an AI tool — means the sensitive version never leaves your control in the first place. It’s the one safeguard a cloud workflow, by definition, can’t offer.

Remove the content, don’t cover it. Real redaction deletes the underlying text and image data so there’s nothing left to copy, paste, or extract. Clearing the document’s metadata is a separate step from removing the visible content — a complete workflow does both. (For why the metadata matters as much as the visible text, see how most PDF redaction quietly fails.)

Catch what the eye misses, then decide. Automatic detection of the common identifiers — SSNs, account numbers, dates of birth, medical record numbers, emails — surfaces the items you’d skim past, and leaves the call to you: each match is something you confirm or dismiss, so you stay in control of the file. That’s Lex Cloak’s job: it finds and removes sensitive information in PDFs entirely on your machine, and lets you check the text is actually gone before you send.

Keep a record of what you did. “Reasonable efforts” is a standard you may one day have to demonstrate. Being able to show which identifiers were found and removed, and that the file was handled locally, is the difference between asserting you were careful and showing it.

The bottom line

The question Rule 1.6(c) puts to you isn’t whether your files contain protected client information — in litigation and transactional work alike, they do. It’s whether you can show you took reasonable, unobtrusive steps before those files left your hands. A redaction workflow that runs on your own machine, removes rather than masks, and gives you a record of the work is a strong, low-cost step in that direction: the information is sensitive and the safeguard is cheap and unobtrusive, which are exactly the factors Comment [18] weighs. Whether any given measure counts as “reasonable” is always fact-specific, and other law may ask for more — but this is squarely the kind of effort the rule is looking for.

See how Lex Cloak redacts a file, start to finish →

This guide is general information about a professional-responsibility rule, not legal advice, and doesn’t create an attorney-client relationship. Ethics rules vary by state, and how Rule 1.6 applies to your situation is a question for your bar association or your own counsel.

Sources

1. American Bar Association, Model Rules of Professional Conduct, Rule 1.6 — Confidentiality of Information: subsection (c) (the rule text) and Comment [18], “Acting Competently to Preserve Confidentiality,” which states the safe harbor and lists the reasonableness factors quoted above. rule text, comment. This is the ABA model rule; individual states adopt their own versions, and the comment numbering has shifted over time — some sources predating later amendments cite these factors under an earlier comment number. ABA Model Rules, current published version, accessed July 14, 2026.
2. The confidentiality-safeguard duty in Rule 1.6(c) and the Comment [18] factors were added by the ABA Commission on Ethics 20/20’s 2012 amendments, which updated the Model Rules for technology and electronically stored client information. ABA Commission on Ethics 20/20
3. Federal Rule of Civil Procedure 5.2, “Privacy Protection for Filings Made with the Court” — requires redaction of Social Security and taxpayer-ID numbers to the last four digits, birth dates to the year, minors’ names to their initials, and financial-account numbers to the last four; it applies to documents filed with the court, including exhibits and material filed in discovery. Many state courts have adopted parallel rules. Cornell LII. Current Federal Rules of Civil Procedure, accessed July 14, 2026.
4. HIPAA Privacy Rule, “Safe Harbor” de-identification method, 45 C.F.R. § 164.514(b)(2), which enumerates the eighteen identifier types (including names, dates, medical record numbers, and account numbers) that must be removed to de-identify protected health information. eCFR. Current eCFR version, accessed July 14, 2026.
5. ABA Standing Committee on Ethics and Professional Responsibility, Formal Opinion 477R (2017), “Securing Communication of Protected Client Information” — a lawyer may transmit information relating to a representation electronically where the lawyer makes reasonable efforts to prevent inadvertent or unauthorized access, weighing the same factors as Comment [18]. ABA Formal Opinion 477R. Issued 2017; the operative opinion (477 was revised to 477R); not superseded as of July 14, 2026.

The rules, regulations, and ethics opinions cited above are living authorities that are amended and occasionally superseded over time. The descriptions here reflect the versions in effect and were verified against the primary sources on July 14, 2026 (the “as of” date for each citation). Confirm the current version before relying on any of them.