WASHINGTON — A federal judge has ordered McGraw-Hill Cos. to turn over some, but not all, documents requested by regulators as part of an investigation into energy price manipulation.

The Commodity Futures Trading Commission in April filed a motion in U.S. District Court for the District of Columbia, seeking to enforce a December subpoena on McGraw-Hill, which refused to produce some documents.

The agency is investigating whether an unnamed energy company manipulated natural gas prices by submitting false information to Platts, a McGraw-Hill subsidiary, for use in Inside FERC, a trade publication that compiles a monthly report on the gas market.

In an Aug. 27 ruling in CFTC v. McGraw-Hill Cos., Judge Ricardo M. Urbina ordered McGraw-Hill to produce some, but not all, of the documents the agency requested.

The CFTC announced the decision on Aug. 30, saying it “marks the fourth time that McGraw-Hill has been compelled by a federal court” to comply with subpoenas. According to the CFTC, the other three cases were CFTC v. McGraw-Hill Cos., 390 F. Supp.2d 27 (D.D.C. 2005); CFTC v. Whitney, 441 F. Supp.2d 61 (D.D.C. 2006); and CFTC v. Bradley, et al., Case No. 05-cv-62, 2006 WL 2045847 (N.D.Okla. July 20, 2006).

McGraw-Hill had argued that the documents requested by the CFTC were protected under the reporter’s privilege.

Urbina, however, ruled that most of the CFTC’s “document requests do not offend the reporter’s privilege or impose an undue burden on McGraw Hill.”

But Urbina did reject one of the CFTC’s requests, saying it was “an unlicensed fishing expedition into McGraw-Hill’s records — precisely the sort of abuse from which the privilege shields reporters.”

Steven Weiss, a McGraw-Hill spokesman, said in an e-mail that the company was pleased with the ruling, because it cut back on the agency’s “overreaching” requests.

“The court once again confirmed that Platts is entitled to the First Amendment protection of the reporter’s privilege,” he wrote in response to a reporter’s question.