Center for Information Technology Policy (CITP) have posted a very interesting article "Studying the Frequency of Redaction Failures in PACER". As most of you know, PACER is the US Federal Courts program for access to court case management and case documents that have been either E-filed or scanned. CITP author Timothy B. Lee explains the differences in PDF and other formats that are used in electronic document systems and the software they developed to study the problem (which they make available). The article ends with a discussion on technical approaches that could be used to address the redaction issue.
In addition, there are other technical resources available. For example, if you use Adobe Acrobat Pro one might want to check out a couple of web pages and videos on subject here and here.
Today courts are often placing the burden of redaction upon the litigants. The Wyoming courts have earlier this year released new rules on document redaction that can be viewed here.
And other redaction rules have been posted by the following courts:
the publically available picture of a redacted page from the ACLU vs. Ashcroft lawsuit.