I often review regulations and legislation that have been certified by the Superintendent of Documents. I've used Acrobat Pro in the past and was able to run OCR to at least allow for commenting/notes, highlighting text and creating my own bookmarks. When I click on the Recognize Text section it is greyed out. Thank you for your help.
If you're talking about a document that was signed with a certification signature, the signer can specify what restrictions should be enforced (e.g., "annotations, form fill-in, and digital signatures" or "No changes allowed"). So first check to see what changes are allowed by the signature, which you can determine by looking at the signature properties. Otherwise, check to see what security restrictions are in place by opening the file in Acrobat and selecting: File > Properties > Security