When does a patent expire?

As an initial matter, it is not clear what type of patent is at issue, i.e., design or patent. Design patents, unlike utility patents, have a term of 14 years from the date of issue. Furthermore, it is not stated in the question whether or not maintenance fees have been paid. Utility patents require the payment of maintenance fees to keep them in force. All of these factors affect patent term. Finally, it should be noted that "Status Date" is irrelevant for patent term purposes as it is merely a date in time for which the status description was last updated in the United Stated Patent and Trademark Office Patent Application Information Retrieval (PAIR) system. For the purposes of this discussion it will be assumed that "Status Date" was meant to be "Issue Date", i.e., the date on which the patent issued. Issue date is relevant for patent term. We will also assume that patent at issue is a utility patent and that all 3 maintenance fees have been timely paid. Accordingly, for applications filed before June 8, 1995 and for patents that were still in force on June 8, 1995, the patent term is either 17 years from the issue date or 20 years from the filing date of the earliest U.S. or international (PCT) application to which priority is claimed (excluding provisional applications), the longer term applying. Here, we have a "Filing or 371(c) date" of November 22, 1993. Using the 20 years from filing date rule, the patent term would end, November 22, 2013, which as of this writing implies that the patent has not yet expired, but will do so later this year. Using the 17 years from issuance rule, the patent term would end, March 7, 2013, which as of this writing implies that the patent has expired. Actual patent term is the longer of the two, i.e., November 22, 2013. Accordingly, with the assumptions stated, the patent is not expired as of this writing. As always, you should seek the advice of patent counsel to further clarify your particular fact scenario and so that he/she can correctly advise you to achieve your business objectives.

For patents filed prior to June 8, 1995, the term of patent is either 20 years from the earliest filing date (excluding provisional applications) or 17 years from the issue date, whichever is longer. Extensions may be had for certain administrative delays.

There is missing information from PAIR in your question. What was the "status" patented case? If "patented" when did the patent issue? What was shown by the "continuity" tab? was a continuation application filed and issued? Based on your facts the general rule of patent term is 20 years from the filing date or 17 years from the issue date whichever is longer. This is due to the filing date being before June 8, 1995 - the GATT date.

You ask an excellent question! For Patents resulting from Patent Applications filed on or after June 8, 1995, the term is 20 years from the filing date of the earliest Patent Application in the chain. This was changed from the 17 years from the date of the Patent grant, which you allude to in your question. The U.S. Patent Office guarantees prompt responses (see 35 U.S.C. 154). If the issue of a Patent is delayed due to the failure of the U.S. Patent Office to respond in a timely manner, the term of the Patent is adjusted accordingly. Because of significant backlog of pending applications at the U.S. Patent Office, the majority of newly issued patents receive some adjustment that extends the term for a period longer than 20 years. The cover sheet of the Patent indicates the number of days that have been added to the patent term. This assumes, of course, that all maintenance fees are paid.