What Is a Vaughn Index in FOIA Litigation?

A Vaughn Index is a document a federal agency must file in a Freedom of Information Act lawsuit that lists every record it is withholding, identifies the FOIA exemption claimed for each one, and explains why disclosure would cause the harm that exemption is meant to prevent. It exists so a judge and the requester can test the government’s secrecy claims against something concrete, rather than accepting a blanket assurance that the records are exempt.

Why the Index Exists

Before 1973, an agency could defeat a FOIA suit with a single official’s affidavit stating in general terms that the requested documents were exempt. The requester had never seen the records and had almost nothing to argue with. Courts had little more.

That practice ended with Vaughn v. Rosen, 484 F.2d 820 (D.C. Cir. 1973). Robert Vaughn, a law professor researching federal civil service practices, sought evaluation reports from the Civil Service Commission. The agency’s justification was a single director’s affidavit offering conclusory opinions about why the records were exempt, with no document-by-document breakdown. The trial court granted summary judgment for the government.¹

The D.C. Circuit reversed. It held that an agency withholding records under FOIA must produce a detailed itemization that lets the judge decide the case rationally without personally reading every document, creates a record capable of appellate review, and gives the requester enough information to argue the case.² That itemization is what practitioners and courts now call a Vaughn Index. The framework shifted the practical burden of specificity onto the party that actually has the documents.

What Each Entry Must Contain

A properly constructed Vaughn Index addresses three things for every withheld document or redaction, plus a fourth question about whether anything can still be released.

Document description. Title, date, author, recipients, and general subject matter, detailed enough to give context without revealing the protected content. For emails and other electronic records, this includes metadata like timestamps and distribution lists. Courts have found indices adequate when they provided the sender, recipients, date and time, and subject for each record.³ An entry that simply says “internal memorandum” gives the court almost nothing to evaluate.

Exemption claimed. The specific FOIA exemption invoked, drawn from the nine statutory categories at 5 U.S.C. § 552. These cover, among other things, classified national security information, records shielded by another federal statute, trade secrets and confidential business information, internal agency communications protected by legal privileges such as the deliberative process, and law enforcement records where disclosure would cause specific harm.⁴

Justification. An explanation of why disclosing this particular document would cause the kind of harm the exemption is designed to prevent. Conclusory justifications, the exact problem the Vaughn court set out to fix, remain the most common reason indices fail judicial review.

Segregability. Beyond those three, the index must address whether any non-exempt portion of a withheld document can be separated from the exempt material and released on its own. Courts expect the agency to indicate, for each record, that all reasonably separable non-exempt information has been disclosed.³ This is the step agencies most often botch. When a document is withheld in full, the index must explain why nothing in it can be safely separated. Skipping the analysis gives the court a reason to doubt every entry.

Agencies typically pair the index with sworn declarations from officials who have direct knowledge of the withheld records, providing context the entries alone may not carry.

When the Index Gets Filed

There is no fixed point in every FOIA lawsuit when a Vaughn Index automatically becomes mandatory. It is triggered by court order or by the natural rhythm of the case, and in practice it almost always surfaces at the summary judgment stage. That is the moment when a judge must decide whether the agency’s exemption claims hold up.

The typical sequence: the requester files a FOIA request, the agency withholds records, the requester sues, and negotiations follow. If the parties reach an impasse, they agree to a briefing schedule. The agency files its motion for summary judgment along with the Vaughn Index and supporting declarations, and the requester responds by attacking any deficiencies. Courts have set explicit litigation schedules requiring the index alongside the summary judgment motion, with a defined window for the requester to reply.³

Judges have flexibility. A court may deny a request for a Vaughn Index when its purpose has already been served through other means, such as the court’s own private review of the documents. In at least one federal circuit, no Vaughn Index is required when the agency relies on the law enforcement exemption to justify its withholdings.³

How Judges Evaluate the Index

FOIA starts from the premise that government records are public. Withholding is the exception, and the agency carries the full burden of proving each exception applies. Courts review the question fresh rather than deferring to the agency’s judgment.⁴ The Vaughn Index is the agency’s primary tool for carrying that burden.

Judges look at two things: whether the index is specific enough to assess each exemption claim, and whether the claimed exemptions actually fit the documents described. Specificity is where most disputes begin. An entry that says only “internal memorandum, Exemption 5” without explaining the deliberative process it would reveal, or the legal advice it contains, tells the court almost nothing. The more detail the agency provides while still protecting the underlying content, the more likely the court accepts the withholding.

When the index and declarations are detailed enough, the court can resolve the case on summary judgment without ever seeing the withheld records. When they fall short, judges have options. They may order the agency to file a revised, more detailed index. They may also conduct an in camera review, privately examining some or all of the withheld records to verify the exemption claims. One court ordered in camera review after giving the agency a final chance to strengthen its declarations and Vaughn Index and finding that problems remained even after supplementation.⁵

When the Index Falls Short

An inadequate Vaughn Index puts the agency in a losing position. The most common outcome is an order to revise and resubmit with more specific justifications. One court rejected an agency’s index because it relied on conclusory assertions and failed to address segregability, ordering an amended version along with a new supporting declaration.³ That buys the agency more time but adds cost and signals to the court that the first effort was insufficient.

When even a revised index cannot justify the withholdings, the court can order disclosure. This is the outcome agencies most want to avoid, and it happens when entries are so vague or poorly supported that the court has no factual basis to sustain the exemptions. FOIA also allows courts to award reasonable attorney’s fees and litigation costs to a requester who substantially prevails, whether through a court order, a written settlement, or a voluntary change in the agency’s position prompted by the lawsuit.⁴

Categorical Indices and Sampling in Large Cases

When large numbers of documents are withheld for the same reason, some agencies produce a categorical Vaughn Index. Rather than index every record individually, they group similar documents into defined categories, explain the exemption justification for each category, and mark individual documents with the applicable code. Courts have accepted this approach for pages withheld in full under a uniform rationale, such as thousands of pages of law enforcement interview notes withheld under the same exemption.³ The categories must be defined precisely enough that the court can evaluate each one on its merits. A single category called “miscellaneous exempt records” would defeat the purpose.

Representative sampling is another option when volume makes full indexing impractical. In one case involving more than 23,000 pages, the judge directed the agency to index every 84th page, roughly two percent of the total, as a minimum sample, and to substitute the next redacted document whenever the selected page had already been released in full. The court required the index to explain not just why each sampled page was withheld, but also why the entire document containing that page was exempt.³ Sampling has also been allowed in cases with much smaller volumes, so the technique is not reserved only for massive disclosures.

Electronic Records and Metadata

Most federal records now exist as email, spreadsheets, database exports, and other electronic files. The shift changed what agencies have to describe. Paper documents had authors, dates, and file locations. Electronic records add layers of metadata: email headers, timestamps, distribution lists, file properties. Courts expect to see that information in a well-prepared index. An entry identifying a withheld record as “an email from [sender] to [recipients] on [date] regarding [subject]” gives the court far more to work with than one that lists “electronic communication, Exemption 5.” As agencies generate more digital records, the quality bar for Vaughn Indices continues to rise alongside the records they describe.

1
Justia. Robert G. Vaughn v. Bernard Rosen, 484 F.2d 820 (D.C. Cir. 1973)
2
U.S. Department of Justice. Advanced FOIA Litigation
3
U.S. Department of Justice. FOIA Guidance and Resources – Court Decisions – Vaughn Index
4
Office of the Law Revision Counsel. 5 USC 552 – Freedom of Information Act
5
U.S. Department of Justice. FOIA Guidance and Resources – Court Decisions – In Camera Review