AI Hallucinations in Law: Why Courts Are Sanctioning Lawyers Using ChatGPT

The Illusion of Confidence in AI Legal Tools

There’s a moment that happens when you use AI for legal work.

You ask a question. It responds clearly. It cites authority. It sounds confident—sometimes more confident than a junior associate on a deadline.

It feels like progress.

But courts are now documenting something more precise—and more dangerous:

Confidence is not accuracy.

Large language models do not verify truth. They generate language based on statistical patterns. In most contexts, that distinction is manageable.

In legal practice, it is not.

A Defining Case: Fabricated Law in Federal Court

Mata v. Avianca, Inc.

In 2023, the U.S. District Court for the Southern District of New York reviewed a filing that appeared routine. It cited multiple cases, followed standard structure, and presented coherent legal reasoning.

The citations were entirely fabricated.

Counsel had relied on AI-generated research that produced non-existent cases, complete with quotations and legal analysis. The submission was not verified prior to filing.

Outcome

• Monetary sanctions imposed
• Mandatory disclosure to affected courts
• Formal judicial opinion addressing AI misuse

The court emphasized that the issue was not the use of AI itself, but the failure to verify authorities before submission.[1]

This case is now widely recognized as the first major sanction tied directly to AI hallucinations in legal filings.

A Pattern Emerges: AI Misuse Extends Beyond One Case

Michael Cohen Filing Incident (2023)

In a separate federal matter, counsel for Michael Cohen submitted a filing containing AI-generated citations that did not exist. The attorney later acknowledged reliance on generative AI tools and moved to correct the record.[2]

Outcome

• Filing withdrawn and amended
• Public disclosure of AI reliance
• Reputational and procedural consequences

While not resulting in formal sanctions identical to Mata, the incident reinforced a broader pattern:

AI-generated legal hallucinations are not isolated—they are recurring.

Judicial Response: Formal Safeguards Are Emerging

Standing Order by Brantley Starr

In response to growing concerns, Judge Starr issued a standing order requiring attorneys to certify that:

• No AI-generated content has been used without verification
• Or that all AI-assisted material has been reviewed by a human for accuracy[3]

Why This Matters

This is not a theoretical concern. It represents:

• A procedural adaptation by courts
• A formal acknowledgment of hallucination risk
• A reinforcement of existing professional obligations

Courts are not banning AI.
They are tightening accountability around its use.

What AI Hallucinations Actually Are (And Are Not)

Definition

An AI hallucination is the generation of:

• Non-existent legal authorities
• Incorrect case law interpretations
• Plausible but false citations

These outputs are not errors in the traditional sense.

They are statistically coherent fabrications.

Why They Occur

AI systems:

• Do not access a verified legal database in real time (by default)
• Do not distinguish binding vs. persuasive authority
• Do not validate citations against court records

They optimize for linguistic plausibility, not legal accuracy.

What AI Hallucinations Actually Are (And Are Not)

Definition

An AI hallucination is the generation of:

• Non-existent legal authorities
• Incorrect case law interpretations
• Plausible but false citations

These outputs are not errors in the traditional sense.

They are statistically coherent fabrications.

Why They Occur

AI systems:

• Do not access a verified legal database in real time (by default)
• Do not distinguish binding vs. persuasive authority
• Do not validate citations against court records

They optimize for linguistic plausibility, not legal accuracy.

The Legal Failure: Process, Not Technology

Across verified incidents, the breakdown is consistent.

What Did Not Happen

• No independent case verification
• No Shepardizing or citation validation
• No procedural review before filing

What Courts Are Enforcing

Existing legal duties remain unchanged:

• Duty of competence
• Duty of candor to the tribunal
• Federal Rule of Civil Procedure 11 obligations

AI does not alter these duties.
It increases the risk of violating them when misused.

Where AI Adds Legitimate Value in Legal Workflows

Used correctly, AI can improve efficiency without compromising integrity.

Appropriate Use Cases

• Drafting preliminary arguments
• Structuring legal writing
• Summarizing large documents
• Preparing clients for consultation

In these contexts, AI functions as:

A thinking partner, not a source of authority

Where AI Introduces Legal Risk

AI becomes dangerous when used for:

Authority Determination

Identifying what the law is without verification

Case Selection

Choosing applicable precedent without validation

Final Work Product

Submitting outputs without human review

At this point, the user is no longer using a tool.

They are delegating responsibility to a system that cannot assume it.

The Cognitive Risk: False Certainty

AI does not signal uncertainty effectively.

Its outputs are:

• Fluent
• Structured
• Complete

This creates a subtle but critical shift:

Traditional Research	AI Interaction
Encourages skepticism	Encourages acceptance
Requires verification	Feels self-contained
Reveals gaps	Masks uncertainty

In legal practice, this shift can result in:

• Undetected errors
• Misstated law
• Procedural violations

Implications for Lawyers and Clients

For Legal Professionals

AI should be treated as:

• A drafting accelerator
• A research assistant (with verification)
• A productivity tool

It should never be treated as:

• A legal authority
• A decision-maker
• A substitute for professional judgment

For Individuals Using AI for Legal Questions

AI can help you:

• Understand legal terminology
• Frame your situation
• Prepare for professional advice

It cannot:

• Replace legal counsel
• Account for jurisdictional nuance
• Assume responsibility for outcomes

The Direction of the Legal System

The response from courts is consistent and measured.

They are:

• Allowing AI use
• Requiring human verification
• Enforcing existing standards

This is not resistance to innovation. It is preservation of legal integrity under new conditions.

Final Takeaway

AI is powerful—but it must be used with precision.

Not a source of truth
Not a legal authority
Not a substitute for expertise

It is a tool for iteration.

Use it to:

• Think more clearly
• Prepare more effectively
• Engage legal experts more intelligently

But when the stakes are real—and they usually are—

Verification is not optional. Responsibility is not transferable.

Footnotes

[1] Mata v. Avianca, Inc., No. 22-cv-1461 (S.D.N.Y. June 22, 2023), sanctions order. Available via CourtListener: https://storage.courtlistener.com/recap/gov.uscourts.nysd.575368/gov.uscourts.nysd.575368.54.0.pdf

[2] Reuters, “Trump’s ex-lawyer Michael Cohen cites fake cases generated by Google Bard,” Dec. 29, 2023: https://www.reuters.com/legal/trumps-ex-lawyer-michael-cohen-cites-fake-cases-generated-by-google-bard-2023-12-29/

[3] Reuters, “Judge orders lawyers to certify they did not use AI or checked it,” May 30, 2023: https://www.reuters.com/legal/judge-orders-lawyers-certify-they-did-not-use-ai-or-checked-it-2023-05-30/