Declassification of classified government information can be a sensitive matter, and specific examples depend on the context and the nature of the information involved. However, there are instances when classified information has been declassified to provide greater transparency in government, expose wrongdoing, or provide historical context to events.

One example of classified information that has been declassified is the Pentagon Papers, a classified report on the history of U.S. involvement in Vietnam from 1945 to 1967. In 1971, a former military analyst leaked the report to the New York Times, exposing the U.S. government's misleading statements about the war. The release of the Pentagon Papers fueled public opposition to the war and led to a landmark legal case that established the freedom of the press to publish classified information of public interest.

Another example is the declassification of information related to the Watergate scandal. The release of classified information related to Watergate helped to expose the illegal activities of the Nixon administration, leading to the resignation of President Nixon.

Overall, the declassification of classified government information should be made carefully and on a case-by-case basis, weighing the potential benefits of transparency against the risks to national security or other sensitive matters.