[paulhart]

There have been many instances where PDFs have been "redacted" by painting black rectangles over the text, but keeping the text intact. I can't think of anyone who has been prosecuted for unredacting those documents - the people who did their jobs poorly are considered liable.

[OJFord]

A barebones PDF reader implementation would/could not render that 'layer' anyway, so I can't imagine you'd actually lose such a case. (As distinct from not having the will/funds to fight it long enough...)