This is not related to GDPR afaics, but at least in Germany, there is an IT security law that governs how companies must disclose security breaches. (Don't get your hopes up, that law is entirely toothless in practice.)
The only true safe way is to print it, redact with a sharpie and scan it back in. Not everyone is versed enogh with Adobe acrobat to do it the right way.
1) Irrelevant in the case of this court filing as the lawyer's name is attached
2) In the case where this might be relevant there's a much easier way - export PDF pages to high resolution PNG, edit to put a black box over the text, and then combine the PNGs into a PDF again. This also has the benefit of stripping any PDF metadata that may have been present in the original.
FWIW, (2) doesn't strip any sort of steganographic watermark that might already be embedded in the document, but invisible to the naked eye. Of course, there's no reliable way to do that, anyway. And steganography could be used in ways that are visible to the human eye (i.e., survives printing/scanning) but still imperceptible with a single copy of the document.
Not necessarily! Consider rearranged words or punctuation in different versions of the document. You'd have to do something like type up a paraphrase to get around that.
Redacting with sharpie migh still leave the text visible via gamma futzing or other photoshop tricks. Print-exacto knife-scan is an improvement on print-sharpie-scan.
Export the page in question to a raster image format like PNG at a high resolution, use an erasing tool on it, re-import the whole thing as a high-res raster (not OCR).
In the past 15 years I have seen so many poorly redacted PDF from government agencies, where they just draw a black box over the PDF-native text.
This is a combination of things I'm most familiar with and things I'd build shit in if not for the fact that other devs at my company aren't familiar with it. i.e. We use MySQL everywhere, so I can't just spin up a new project using Postgres for the sake of consistency.
