I got this from slashdot
The U.S. government released in PDF format a
redacted version of their court filing in the Balco grand jury leak case. But they only stuck a black line over the text in Acrobat. The underlying text remains available in the PDF file. From Adobe Acrobat, simply select all (CTRL-A), then copy (CTRL-C), then go to a text editor and paste (CTRL-V). The redacted text is now visible.