In the rapid progression of the Pentagon Papers from newspaper revelation to court case to judgment by the Supreme Court of the United States during a few weeks in June 1971, the Nixon administration failed to stop the presses. The Justice Department made two major submissions to Courts on exactly what information in the history "United States-Vietnam Relations 1945-1967" was so sensitive that it justified keeping secret the entire forty-seven part history. One of these submissions was to the Supreme Court made by Erwin N. Griswold, Solicitor General of the United States, which identified 11 drop-dead secrets. The other, which Griswold incorporated into his text, was made in New York City to the United States Court of Appeals for the Second Circuit, which identified 17 irreparably damaging secrets.

http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB48/briefs.html