From Nat’l Day Laborer Organizing Network v. U.S. Immigration and Customs Enforcement Agency, 2011 U.S. Dist. LEXIS 11655 (S.D.N.Y. Feb. 7, 2011):

No federal court has yet recognized that metadata is part of a public record as defined in FOIA. However, this precise issue has been addressed by several state courts, which have uniformly held, in the context of state freedom of information laws, that metadata is indeed a part of public records and must be disclosed pursuant to a request for public records.

[Footnote 26] See Irwin v. Onondaga Cnty. Res. Recovery Agency, 895 N.Y.S.2d 262, 319 (4th Dep't 2010) (finding that petitioner's request for "all computer records that are associated with published [photographs]" included a demand for the metadata associated with those images, and that the metadata should have been disclosed pursuant to New York's Freedom of Information Law); O'Neill v. City of Shoreline, 240 P.3d 1149, 1152 (Wash. 2010) (holding, in a manner of first impression, that metadata associated with an e-mail sent to a public official constituted a public record subject to disclosure under Washington's Public Records Act); Lake v. City of Phoenix, 218 P.3d 1004, 1007-08 (Ariz. 2009) ("[T]he metadata in an electronic document is part of the underlying document; it does not stand on its own. When a public officer uses a computer to make a public record, the metadata forms part of the document as much as the words on the page.").

***

The Government argues that metadata is substantive information that must be explicitly requested and then reviewed by an agency for possible exemptions. Because there is no controlling FOIA precedent recognizing that metadata is an integral part of the electronic record that must be produced when an electronic record is requested, the Government asserts that it complied with its FOIA obligations, even if it did not comply with the Rules. To that end, the Government argues that if the requirements of FOIA and the requirements of the Rules conflict, FOIA must trump the Rules. However, there is no need to decide this question because FOIA does not conflict with the Rules. FOIA is silent with respect to form of production, requiring only that the record be provided in "any form or format requested by the person if the record is readily reproducible by the agency in that form or format." There is no doubt in my mind that this language refers only to technical ability or, at most, reasonable accessibility. Defendants do not argue that they are unable to produce the records in the requested form — namely native format for spreadsheets and single file format for text records — but that reviewing all of the metadata would greatly increase the burden of search and production. To that extent, they have unwittingly argued that a request to produce all metadata would push the request into the second tier of Rule 26(b)(2)(B) because such records are not reasonably accessible based on undue burden and cost.

Nonetheless, the Government argues that FOIA is not synonymous with discovery in a civil litigation. It is a statute requiring the production of records to the public, upon request, subject to certain exemptions. While rhetorically nuanced, this argument is unavailing. Regardless of whether FOIA requests are subject to the same rules governing discovery requests, Rule 34 surely should inform highly experienced litigators as to what is expected of them when making a document production in the twenty-first century. As noted earlier, Defendants' productions to date have failed to comply with Rule 34 or with FOIA. ***

[W]hile native format is often the best form of production, it is easy to see why it is not feasible where a significant amount of information must be redacted. **

That said, I now hold, consistent with the state court decisions cited earlier, that certain metadata is an integral or intrinsic part of an electronic record. As a result, such metadata is "readily reproducible" in the FOIA context. The only remaining issue is which of the many types of metadata are an intrinsic part of an electronic record. Unfortunately, there is no ready answer to this question. The answer depends, in part, on the type of electronic record at issue (i.e., text record, e-mail, or spreadsheet) and on how the agency maintains its records. Some agencies may maintain only a printed or imaged document as the final or official version of a record. Others retain all records in native format, which preserves much of the metadata. Electronic records may have migrated from one system to another, maintaining some metadata but not all. The best way I can answer the question is that metadata maintained by the agency as a part of an electronic record is presumptively producible under FOIA, unless the agency demonstrates that such metadata is not "readily reproducible."