A patent examiner issues a restriction requirement for a filed patent application when the examiner believes that there are multiple distinct inventions in the application’s claims and that examination of all of those distinct inventions would constitute an undue burden on the examiner. The restriction requires that the applicant to “elect” one of the various groups of claims that the examiner has identified. Thereafter, the examiner will further consider only the elected group of claims.
You (via your patent practitioner) can respond by electing one of the groups of claims that the examiner has identified in the restriction requirement. If you disagree with the restriction requirement — e.g., if you believe that the identified inventions are not truly distinct, or that examining all of them together would not place an undue burden on the examiner — you may additionally argue that the restriction is incorrect. If the examiner remains unconvinced, then only the claims you elected will be examined initially.
Although in most cases the examiner will not examine the non-elected claims in the current patent application, there are still various avenues to pursue the other claims. For example, you can file a “divisional” patent application to containing the non-elected claims. “Divisional” applications are relatively inexpensive to prepare and file (since the application and claims have already been written), and can be filed any time until the first application is granted.
To learn more about restriction requirements and how to respond to them, don’t hesitate to call or e-mail anyone on your Fenwick prosecution team.
For even more details, you can consult Chapter 800 of the Manual of Patent Examining Procedure (MPEP).