In any given courtroom throughout the U.S., there are thousands of pages of legal documents filed every day. Although attorneys are well trained and well educated, and often employ well trained and experienced paralegals to assist them, the tremendous amount of paperwork makes it inevitable that errors will eventually appear. While it may be somewhat embarrassing, a conscientious attorney (or litigant) has a duty to quickly report and correct errors before the court upon learning of their existence.
Determine whether the typographical error requires correction. While a court will appreciate the candour of an attorney or litigant admitting an error in a document they have filed, going through the process of refilling a legal document isn't worth it unless there's a meaningful error. A misspelling of "jurisdiction" or "probable cause" is not likely to obscure the meaning of the word and therefore does not require correction. However, including an incorrect case citation or statute, or a typo that constitutes a material error (such as an incorrect address) will likely require immediate correction.
Take advantage of the "one free do-over" rule. Under Rule 15 of the Federal Rules of Civil Procedure (applicable in federal court), a party that has submitted a pleading before trial may amend that pleading within 21 days of serving it on the opposing party. If the document before the court with a typo requires a response, a party may amend within 21 days of the responsive pleading. A party may amend the pleading to fix the typo without the permission of the judge or opposing counsel. Furthermore, almost all state civil procedure rules are based off the Federal Rules of Civil Procedure, and contain a liberal provision for refilling similar to Rule 15.
Notify opposing counsel and the judge. While Rule 15 may not require notifying opposing counsel and the judge that you are correcting a typo, it is still good practice to do so.
Ask the judge to allow you to refile the document if it is beyond the 21 day limit: Rule 15 of the Federal Rules of Civil Procedure (and most state rules of civil procedure) allow a party to refile "with the opposing party's written consent or the court's leave." Often, calling opposing counsel and explaining the nature of the typo will result in opposing counsel granting written permission to correct the error. If not, a judge is obligated to give permission to correct errors "when justice so requires." Practically speaking, while this does not mean automatic permission to refile and correct the typo, a judge will almost always grant permission.
Fix the error and resubmit the legal document correctly. While judges and opposing counsel will often appreciate the candour of an attorney or litigant admitting an error, they are much less likely to appreciate repeating the same error. After complying with Rule 15 or obtaining permission from the court or opposing counsel, fix the error. Double check your work or have an experienced paralegal do this for you. After making sure the error is fixed, refile the document with the court clerk.