Department of Interior v. Klamath Water Users Protective Assn., 532 U.S. 1 (2001), was a United States Supreme Court case decided in 2001.

The case concerned whether Exemption 5 of the Freedom of Information Act, which applies to "intra agency memoranda or letters", is applicable to documents within the Department of the Interior which discussed plans for the allocation of water in the Klamath River Basin.

[1] Some documents were turned over, but the Bureau held other documents under the deliberative process privileges incorporated in Freedom of Information Act (FOIA) Exemption 5, which exempts from disclosure "inter-agency or intra-agency memorandums or letters which would not be available by law to a party other than an agency in litigation with the agency.

[3] Justice David Souter wrote the unanimous opinion of the Court which affirmed the Ninth Circuit.

The Bureau officials were working with the Tribe, advocating their interests which meant the documents were not exempt from public disclosure of intra-agency communications.