SigmaCore.ai

Lex - SigmaCore Legal

Every Citation Real. Every Quote Verified. Every Filing Safe.

One fabricated case citation can trigger sanctions, a bar referral, or the end of a legal career. Lex verifies every citation, confirms every quote, and checks that every case is still good law - before you file. In minutes, you get a timestamped Rule 11 compliance certificate that proves you did your due diligence. File fearless.
Built for attorneys who cannot afford to get it wrong.

Michael R., a twelve year federal litigator at a mid sized Atlanta boutique, is staring at a TRO opposition that must be filed by 9:00 AM. It’s 2:00 AM, and although the brief is strong, it contains eighty seven citations — many drafted with the help of an AI tool he used to accelerate the writing. Under normal circumstances, he would spend eight to twelve hours verifying every case, every quote, and every proposition. Tonight he has seven hours until filing, a judge with an AI use standing order, and a professional obligation that leaves no room for error. He knows the risk: courts are sanctioning attorneys for fabricated citations, and one mistake could become a headline, a bar referral, or worse.
Michael uploads the brief into Lex. Within seconds, Lex flags three cases that do not exist in either Westlaw or LexisNexis — hallucinations that slipped into the AI generated draft. Without Lex, those citations would have gone straight into a federal filing. Moments later, Lex highlights two block quotes that don’t match the original opinions: one missing a sentence, another containing language that never appeared in the case. Then comes the third blow — a key authority the AI tool relied on was partially overruled last year. Lex surfaces all of it instantly, and for each issue, it provides verified replacement cases, accurate quotations, and pinpoint citations that actually support the argument. Michael accepts the fixes with a click.
By 2:17 AM, Lex generates a timestamped Rule 11 compliance certificate documenting every database queried, every citation checked, every quote matched, and the exact moment verification occurred. Michael files the brief at 8:54 AM — confident, protected, and fully compliant. In a later hearing, the judge remarks that the brief is “exceptionally well supported and meticulously cited.” What the judge doesn’t know is that Lex quietly prevented Michael from filing three nonexistent cases, two inaccurate quotes, and one overruled authority — all in under twenty minutes. His managing partner mandates Lex firm wide the next day.
Lex didn’t just save a filing. It protected a career.

AI is writing legal briefs. Nobody is checking the citations.

Seventy-nine percent of attorneys now use AI tools in their practice. That number is growing every month. The problem is not that attorneys are using AI — it is that most of them have no systematic way to verify what it produces before it gets filed. AI language models generate citations confidently and incorrectly. They cite cases that do not exist. They quote passages that were never written. They assert that cases stand for propositions they flatly contradict. And they do all of this in perfect legal prose that looks completely legitimate until someone checks.

The consequences are not theoretical. They are happening right now.

Courts across the United States have documented over 1,353 AI hallucination cases in legal filings. In May 2025, K&L Gates and a co-counsel firm were ordered to pay $31,000 — the largest documented AI citation sanction on record — for filing a brief containing fabricated citations and false quotations. In 2025, a Colorado attorney became the first in the United States suspended directly for AI citation misconduct. The ABA issued Formal Opinion 512 in 2024, making citation verification a formal competence obligation under Rule 1.1. Over 200 federal courts have issued AI-specific standing orders requiring disclosure or certification of AI use in legal filings. This is not a future risk. It is a present crisis.

Checking citations manually takes the time you do not have.

Manually verifying every citation in a 150-citation brief — confirming existence, checking Shepard's or KeyCite, matching quoted passages verbatim, and confirming that each case actually supports the proposition for which it is cited — takes eight to twelve hours. Most attorneys are billing those hours, not spending them on citation review. And the pressure to file on time means the check that should happen rarely does.

Westlaw and LexisNexis are research tools, not verification tools.

Westlaw and LexisNexis are excellent for finding law. They are not built to automatically verify every citation in an AI-generated brief, match quoted passages to original opinions, or generate a timestamped compliance record documenting that verification was performed. Shepard's and KeyCite tell you whether a case is still good law. They do not tell you whether the case exists, whether the quoted passage is accurate, or whether the case actually supports the argument being made.

There is no documented proof that you checked.

Even attorneys who do verify their citations manually have no systematic way to document that verification. When a court asks — and courts are increasingly asking — whether AI-generated citations were checked, a verbal assurance is not enough. Rule 11 requires a reasonable inquiry. Without a documented record of what was checked, when it was checked, and against what sources, that inquiry cannot be demonstrated.

Lex was built for the specific problem that AI has created in legal practice: citations that look right but are not, and no systematic way to catch them before they are filed. It connects directly to Westlaw and LexisNexis, checks every citation in your brief, and generates a timestamped compliance certificate - your documented proof that every case was verified before you signed your name to the filing.
Your briefs contain confidential information. Lex processes your documents securely, stores them with encryption, and automatically deletes them after a certain period based on subscription type. Your clients’ information stays yours.

Every Citation Confirmed Real - Against Both Databases

Lex checks every cited case against Westlaw and LexisNexis simultaneously. If the case does not exist in either database, Lex flags it immediately - before you file. This is the check that would have prevented every AI citation sanction that has made the news. It takes seconds per citation. It takes Lex under five minutes for a full brief.

Good Law Status on Every Citation - In Real Time

Every citation is Shepardized and KeyCited in real time. If a case has been overruled, distinguished, or limited, Lex flags it before it appears in a filed brief. Citing overruled authority is a separate liability from citing fabricated authority - and Lex catches both.

Every Quoted Passage Matched Verbatim to the Original Opinion

K&L Gates was sanctioned $31,000 in part because quoted passages in the filed brief did not match what the cited opinions actually said. Lex matches every quoted passage in your brief against the original opinion text, word for word. If the quote is inaccurate - whether it was generated by AI, misremembered, or simply transcribed incorrectly - Lex catches it.

A Timestamped Rule 11 Compliance Certificate - Generated in minutes

After verification, Lex generates a timestamped compliance certificate documenting every database queried, every citation checked, every quote matched, and the date and time of verification. This certificate is your documented evidence of reasonable inquiry under Rule 11. It is your answer when a court asks whether you checked. It is your first line of defense if a citation error is ever alleged. No other product generates this certificate.

Real-Time Checking Inside Your Drafting Workflow

Lex integrates directly with Microsoft Word and Google Docs, flagging citation errors as you draft - not after you finish. This is the feature that breaks the escalation cycle: the pattern that begins with a $5,000 sanction, continues to a $31,000 sanction, and ends in suspension happens because errors were noticed after filing, not before. Catching the error at the moment it is written eliminates the "continued conduct after notice" that courts use to justify escalating penalties.

Suggested Replacements — One Click to Fix

When Lex flags a problem citation, it does not just tell you something is wrong. It searches for verified replacement citations that support the same argument - real cases, good law, correctly quoted - and presents them for one-click insertion. The goal is not just to catch errors. It is to keep your brief moving forward.

For Litigation Attorneys

You are personally responsible for every representation made to the court. The AI tool that drafted your brief is not. Lex gives you the documented verification process that protects your license, your reputation, and your client - in under five minutes per brief.

For Legal Operations Directors

ABA Formal Opinion 512 makes citation verification a firm-wide competence obligation, not an individual choice. Lex gives your firm a documented compliance programme - a systematic, auditable verification process that demonstrates the firm is meeting its professional obligations. That programme matters to your malpractice insurer. It matters to your managing partner. And it will matter to any court that asks.

For Law Firm Managing Partners

One AI citation sanction against a firm associate becomes a headline, a bar referral, and a malpractice claim. Lex deployed firm-wide means every brief filed under your firm's name has been verified, documented, and certified. The cost of Lex is measured in dollars per month. The cost of not having it is measured in sanctions, reputation, and careers.

For Malpractice Insurers

Law firms using Lex have a documented verification process for every AI-assisted filing. That documentation reduces the frequency and severity of AI citation claims - and the data Lex generates gives underwriters visibility into verification practices that no other tool currently provides.

What Lex Produces	What It Replaces
Confirmed existence of every cited case	Sanctions for fabricated citations
Verbatim quote verification	Sanctions for false quotations
Timestamped Rule 11 compliance certificate	Exposure when a court asks if you checked
Firm-wide compliance dashboard	Undocumented AI use across the practice

The Rule Is Simple. The Risk Is Real.

The ABA could not be clearer: using AI to draft a brief does not reduce your obligation to verify what it produces. It increases it. Every attorney who has been sanctioned for an AI citation error believed they were working efficiently. None of them planned to file a fabricated citation. All of them wished they had checked.

Lex checks. In under five minutes. With a certificate that proves it. The ABA could not be clearer: using AI to draft a brief does not reduce your obligation to verify what it produces. It increases it. Every attorney who has been sanctioned for an AI citation error believed they were working efficiently. None of them planned to file a fabricated citation. All of them wished they had checked. Lex checks. In under five minutes. With a certificate that proves it.

Product Features

🔍

Instant Citation Extraction

Upload your brief and Lex gets to work immediately - reading the entire document and pulling every case, statute, and regulation automatically. No copying. No manual checklist. Every citation identified and ready to verify before you have finished your coffee.

⚖️

Bluebook Format Check

Before anything else, Lex checks every citation against Bluebook formatting rules - reporter abbreviations, volume and page numbers, case name formatting. Catch the errors a court clerk will catch. A rejected filing because of a formatting mistake is entirely avoidable. Lex makes sure it is.

💬

Citation Existence Verification

This is your first line of defense against AI hallucinations and clerical errors. Lex checks every citation against multiple federal and state case law databases to confirm the case actually exists. If it does not, you know before you file - not after a judge asks why you cited a case that has never existed.

📜

Good Law Status Check

A case can exist and still get you sanctioned. Lex checks every citation to confirm it is still good law - flagging anything that has been overruled, reversed, or limited by a later decision. Attorneys have faced sanctions exceeding $100,000 for citing overruled authority. One pass through Lex catches it automatically.

⚡

Rule 11 Compliance Certificate

After every verification, Lex generates a timestamped certificate documenting exactly what was checked, which databases were consulted, when verification occurred, and what was found. Courts have reduced or dismissed sanctions when attorneys demonstrate they performed documented due diligence. This certificate is that documentation - generated in minutes, ready to produce on demand.