The timeline for acquiring a patent from the USPTO can vary greatly and often include significant delays in the responsiveness of the patent office. However, generally speaking, the patent office intends to complete prosecution of a patent application within three years of the filing date for the patent application. If delays at the patent office, that are caused by the patent office, result in pendency of greater than three years, each day of delay caused by the patent office can result in the extension of the life of your patent when it issues. The patent term extension laws help prevent a patent owner from unfairly losing time from the life of the patents; however, the extensions do not address any of the issues related to the uncertainty a patent owner experiences during the prosecution of the patent application. Individual experiences can vary greatly as I have filed patent applications that have issued as patents in less than the three year target as well as patents that were not even reviewed substantively a single time within the three year target.
The latest numbers I’ve seen (July 2009), show that approximately half of the patent applications filed most recently have been disposed of in about three and a half years, with nearly 90% of patent applications disposed of within six years.