What is the proper filing date for a pleading in a civil case?

^2. Generally, for incarcerated persons, the filing date is the date on which the pro se prisoner delivers the pleading to prison authorities. See Houston v. Lack, 487 U.S. 266, 275-76, 108 S.Ct. 2379, 2385, 101 L.Ed.2d 245 (1988). In this case, though, while plaintiff's documents are dated August 9, 2009, he does not include a certificate of service to indicate when he actually gave the documents to prison officials for mailing. See Doc. No. 1. Accordingly, the court will not extend the mailbox rule to plaintiff's complaint, and the filing date will be measured as of the date the document was filed in this court.