ChatGPT for Lawyers: The Settings, Plans and Workflows Nobody Walks You Through

In 2025 a Butler Snow partner asked ChatGPT for authorities to support two routine discovery motions. It gave him five. One, Kelley v. City of Birmingham, was fabricated; another, Greer v. Warden, did not exist; a third was a real case with the wrong citation and the wrong proposition. The associate “reviewed the updated draft for grammar and typos”. The firm had had a written AI policy since June 2023. Three of its lawyers were publicly reprimanded, disqualified and referred to the Alabama bar (EDRM on Johnson v. Dunn).

That is the story most guides to ChatGPT for lawyers tell, and it is the wrong lesson. The partner’s mistake was not using ChatGPT; it was using it for the task it is worst at, on settings nobody had shown him, and not reading the result. Fix those three things and the same tool is the most useful software a small firm has bought since Word.

Who uses ChatGPT in law: the numbers

ChatGPT is not a challenger to the legal platforms. It is the incumbent they are trying to displace.

The same Texas survey found 64% worried about fictitious cases and only 9% “extremely confident” evaluating AI output. Damien Charlotin’s database of court decisions involving hallucinated material names ChatGPT in 111 entries and implies it in 1,366 more.

Settings first: Data Controls, Temporary Chat, memory, sharing

Five minutes here removes most of the confidentiality risk on a personal plan; none of it happens automatically.

Data Controls. On Free, Go, Plus and Pro, your conversations train OpenAI’s models unless you turn that off: Settings > Data Controls > Improve the model for everyone > off. The setting syncs across devices (OpenAI Data Controls FAQ).

Temporary Chat. In OpenAI’s words, Temporary Chats “are deleted from our systems after 30 days”, are not used to train models, “don’t create memories”, but “may be reviewed only to monitor for abuse”. Sterling Miller’s hygiene list for in-house lawyers: “Turn off ‘Improve model for everyone’”, “Use ‘temporary chat’”, “Delete all chats every day or on a regular timeframe” (Ten Things, 31 March 2025).

Deletion. A deleted chat is “scheduled for permanent deletion from OpenAI systems within 30 days, unless: the chat has already been de-identified and disassociated from you, or OpenAI must retain it longer for security or legal obligations”. Archiving is not deleting. Files in a Project stay until the Project is deleted (OpenAI retention policies).

Memory. A client name mentioned on Monday can resurface in an unrelated chat on Thursday. Clear memory regularly, and use Temporary Chat for anything you do not want remembered.

The “legal obligations” clause is not theoretical. Under the preservation order in New York Times v. OpenAI, OpenAI kept every deleted and temporary chat of Free, Plus, Pro and Team users from 13 May to 26 September 2025, and in January 2026 Judge Stein affirmed an order to produce 20 million de-identified logs. Only Enterprise, Edu and zero-data-retention API customers were excluded (NYT order guide).

Plans: Free, Go, Plus, Pro, Business, Enterprise for a five-lawyer firm

The plan decides more than the model does. The line runs between personal plans, which train by default, and workspace plans, which do not.

Source: OpenAI’s enterprise privacy page, as read in September 2026.

On Business the managing partner becomes a workspace admin who can see every lawyer’s conversations: useful for supervision, a surprise for staff, so say it in the firm policy. Neither tier gives you privilege: in United States v. Heppner (S.D.N.Y. 2026) a defendant’s exchanges with consumer Claude were held protected by neither privilege nor work product, on reasoning that turned on the provider’s terms, not the brand. The Business versus Enterprise comparison and the confidentiality guide go clause by clause.

Projects and custom GPTs for recurring work

A Project (a workspace with its own files and standing instructions) or a custom GPT (a saved configuration you can share) is where ChatGPT stops being a chat window. OpenAI’s associate general counsel Nicole Diaz, who had never coded, built a “simplify” skill that shortens sentences, cuts legalese and matches her policy templates, and a Codex automation that scans her inbox for conflict-of-interest questions daily and drafts replies from her guidance (Business Insider, June 2026). Encode the judgement once, reuse it a hundred times. Two rules: write the safety rules before the house style, and keep privileged client specifics out of any Project shared across the firm.

Help me write the standing instructions for a reusable ChatGPT Project for my [employment law] practice in [England and Wales]. Interview me with up to 30 questions in batches of ten: my clients and the side I usually act for; the documents I draft most; my playbook positions; how citations must be handled; what must never appear in outputs; my verification routine; how you should behave when unsure.
Then draft the instructions in this order: SAFETY RULES (never invent authorities; tag every legal citation [VERIFY]; write "NOT IN DOCUMENT" rather than guess; ask before assuming jurisdiction); VOICE; JURISDICTION DEFAULTS; HOUSE STYLE; WHAT NOT TO DO; and a short list of anonymised knowledge files I should upload. Under 600 words.

Test it on three past tasks where you know the right answer, then add a “last tested” date. The Projects and custom GPTs guide covers the full build.

Deep Research: what it does in 5 to 30 minutes and how to verify it

Deep Research launched on 2 February 2025 for Pro users, reached Plus later that month, and “may take anywhere from 5 to 30 minutes” to produce a cited report from dozens of web sources (OpenAI). You choose it in the composer, attach PDFs and watch the sources accumulate in the sidebar.

Used well, it is the best first hour on an unfamiliar regulatory topic you can buy. Used badly, it is the Mata brief with footnotes. Research agents “search efficiently, not completely”, as Harvey’s benchmark team put it, so ask what it did not find; and its sources are only as current as the web, so check every date against the official text.

Produce a briefing for a lawyer new to [the EU AI Act's obligations for deployers] as at [today's date]: the governing instruments with official links; who is regulated and who enforces; the compliance timeline with exact dates and any deferrals or amendments in the last twelve months; the three most-cited practitioner summaries from law firms or regulators, linked; the open questions commentators disagree on; a glossary of ten terms.
Prioritise primary sources and law-firm client alerts over news. Put the source next to every date and threshold. End with a section headed "What I could not find or confirm". No more than 1,500 words plus the source list. Cite no case unless you link to the judgement itself.

Then click every source. Deep Research is for orientation, not for citations you will file.

Ten workflows that work (and three that do not)

The ones that work share a shape: you supply the material, you define the output, and you can check the result against something you hold.

Three that do not:

1. Open-web case-law research. Lawyerist’s review: ChatGPT “cannot search case law”. Stanford’s “Large Legal Fictions” study found GPT-4 hallucinating on at least 58% of legal queries, and the Divisional Court in Ayinde v Haringey held that freely available tools such as ChatGPT “are not capable of conducting reliable legal research”. Clio’s headline prompt, “Conduct legal research on [legal issue] and summarize the relevant case law”, is the prompt that invents citations.
2. Whole-document drafting. A share purchase agreement runs 40 to 80 pages of interlocking clauses; UK litigators now see AI-drafted SPAs with warranties sellers “can’t possibly know”. Draft clause by clause (contract drafting guide).
3. Checking its own work. Steven Schwartz asked ChatGPT whether Varghese was a real case; it said the case “can be found in reputable legal databases such as LexisNexis and Westlaw”. The NSW Supreme Court’s practice note: verification “must not be solely carried out by using a Gen AI tool or program”. The same note bans generative AI for affidavits.

A real task, its output and the fixes

Take summarising text, a top use in the Texas survey, and the case that shows it going wrong.

“Bulletproof” asks for confidence; “summary” asks for paraphrase; neither asks for a location you can check. The same task, written so every line points back into the transcript:

Jurisdiction: [New Mexico]. Use only the attached transcript. Do not add facts, witnesses or testimony that do not appear in it.
Summarise the testimony of [witness name] under these headings: (1) statements relevant to [issue], each with page:line; (2) statements that contradict [the other witness / the charging document], in a table: Topic | Page:line | Quoted words | Conflicting source | Nature of inconsistency; (3) internal inconsistencies, with page:line for both statements; (4) questions the witness could not answer or did not recall.
Quote exactly in every "Quoted words" cell. Do not assess credibility. If a heading has no content, write NONE. End with the list of pages you relied on.

Then the check no prompt can do for you: open the transcript at every page:line cited. A summary that cannot be spot-checked is not a summary; it is a story. The same discipline applies to a contract summary: one row per term, a clause-and-page column, and “NOT FOUND” where the document is silent.

The rules: what courts and bars say about ChatGPT

Nothing in the professional rules mentions ChatGPT, and everything applies to it.

• ABA Formal Opinion 512 (29 July 2024). Lawyers “must have a reasonable understanding of the capabilities and limitations”; before inputting client information they “must evaluate the risks that the information will be disclosed to or accessed by others outside the firm”; self-learning tools need informed consent; and “merely adding general, boiler-plate provisions to engagement letters purporting to authorize the lawyer to use GAI is not sufficient” (ABA).
• Courts. Judge Brantley Starr’s standing order requires a certificate that AI-drafted language “was checked for accuracy, using print reporters or traditional legal databases, by a human being”; the Fifth Circuit: “‘I used AI’ will not be an excuse for an otherwise sanctionable offense”. Check your judge’s orders before you file.
• Paying more is not a defence. In Scott v. Illinois Human Rights Commission (2026) the lawyer had a “premier corporate subscription of ChatGPT”. The court: “no matter how much one pays for ‘premier’ or ‘corporate’ versions of AI products, it does not negate an attorney’s obligation to verify all citations of authority.” Sanction: $15,000.
• England and Wales. The Upper Tribunal in UK and Munir v SSHD [2026] UKUT 81 (IAC): to put client letters “into an open source AI tool, such as ChatGPT, is to place this information on the internet in the public domain”. The SRA’s warning notice of 17 August 2026: “Reliance on an output of AI would not be a suitable defence.”

ChatGPT for lawyers vs the alternatives

ChatGPT’s edge is breadth: Deep Research, custom GPTs, the largest user base. Its weakness showed in Vals AI’s October 2025 research benchmark, as reported by LawSites: it matched the legal tools on accuracy (80% against lawyers’ 71%) but trailed on authoritativeness, 70% against 76%, because it does not sit on a legal corpus.

Most lawyers end up with two: ChatGPT or Claude on a business tier for language, and something grounded for authority. The ChatGPT vs Claude comparison settles the first choice; the tools map places the rest.

Where to go next: the prompt library has the standard working-rules header to paste above any client task, plus the ChatGPT versions of every prompt above, and the ChatGPT prompts guide shows them with outputs and critiques. If you would rather do the settings walkthrough, the Project build and the Deep Research check with someone watching your screen, that is what the live sessions of AI Lab for Lawyers are for: taught on ChatGPT, Claude, Perplexity and NotebookLM, no coding, browser tools only. The tools cluster has the head-to-heads.