Pursuant to Section 40 of the Identity Protection Act, 5 ILCS 179/40, passed in 2010 and designed to protect Social Security numbers, the Illinois Supreme Court has adopted new Rule 138 requiring parties not to include Social Security numbers within any filings "unless required for a particular filing". Presumably that means you can't include a Social Security number unless there is a good reason that the number itself matters to a particular filing. Such a situation is hard to imagine because a filer generally should be able to refer to a number's existence without actually spreading the number itself of record. For example, a claim about identity theft could be drafted to satisfy pleading requirements without revealing to the world the actual Social Security number at issue. In any event, if you must include the number the rule requires that you use just the last four digits in the public filing, and accompany it with a sealed filing disclosing the full number.
The rule does not specify how documents that the filer did not create (e.g., photocopied exhibits) that include embedded Social Security numbers should be brought into compliance. However, the wording of the rule implies that the filer should redact the document to make the number unreadable.
Filers should take care that their redaction technique actually accomplishes the redaction, becuase sometimes when you think something has been redacted, the supposedly covered-up information is still accessible. See the Administrative Office of U.S. Courts' admonition here, and an interesting discussion of failed redaction at this blog. The National Security Agency has published some tips on ways to properly redact documents, available here and here. Some district courts have posts about it, such as the District of New Jersey.
The new rule also states that the Illinois courts are not responsible for checking individual filings for compliance. In other words, a clerk is not supposed to take on the responsiblity of checking your filing to see whether you let a Social Security number slip through. The only policing mechanism is that "a party or identified person" who sees that a Social Security number has been publicly filed can move the court to order compliance, and if they prove the infraction was "willful" then they can be awarded fees and costs for bringing the motion. This rule should not spawn a cottage industry of 'file scrubbers' who troll the dockets looking for infractions because only a party to the actual case or the person whose Socual Security number was disclosed appear to have standing to file the motion.
The new rule originally was to be effective starting November 1, 2011. However, the court has now changed the effective date to January 1, 2012.
This rule brings the Illinois courts in line with federal courts, whose Judicial Conference began addressing this issue in 2000 (see their report here), which led to the adoption of rules such as Fed. R. Civ. P. 5.2 (effective Dec. 1, 2007) requiring redacted filings.