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Lapsed patents are patents that expired because the maintenance fee was not paid in due time. Maintenance fees on US patents are due 3.5, 7.5 and 11.5 years after grant of the patent (in many other countries, they are due every year and are called annuities). US patents maintenance fees cannot be paid more than 6 months before the due date. They can be paid ...


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EDIT The PLT has made parts of my answer no longer the state of the law . A patent that has expired due to non-payment of maintenance fees can theoretically be revived by its owner by petition to the USPTO. The grounds are "unavoidable" and "unintentional". The criteria for establishing that it was unavoidable are a high bar: (from 37 C.F.R. 1.378 ) 3) ...


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This is important - A lot of the info on the Internet about this is out of date. They changed the rule on this recently. (Recently = effective December 18, 2013) This web page summarizes the details. http://www.clm.com/publication.cfm?ID=489 The short version is that if a patent holder pays both the maintenance fee and a late fee, they can revive a ...


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