This Article was updated October 21, 2013. See Blog Restriction Practice II. The basic rule is that each patent can claim only one distinct and independent invention. This is subject to the rules pertaining to restriction practice and the filing of divisional applications. A related rule is that two patents can’t claim the same invention. This is subject of the rules prohibiting double patenting and stipulating to terminal disclaimers. See also the article entitled Double Patenting
The first rule can be confusing in implementation. Nearly every patent (excluding design patents) includes multiple claims. Indeed, the basic filing fee pays for up to 3 “independent” claims and 20 total claims (both independent and dependent claims). Part of the confusion arises from inconsistent use of terms.
There are independent patents and there are independent claims within patents.
A patentable invention is defined by the claims. A claim can be either “independent”, i.e., it lists all the limitations or elements of the invention, or “dependant”, i.e., the claim incorporates by reference the limitations or elements listed in another claim.
An independent invention is an invention that is not dependant or related to another invention. An independent invention is unrelated in “design, operation or effect” to another subject disclosed in the application. This can be confusing because, in general terms, everything is related to something else.
The USPTO Manuel of Patent Examining Procedure (MPEP) tries to provide some explanation (See MPEP Chapter 8 at §806.04.) Two different combinations (of elements) are independent if they are not disclosed (in a patent application) as being capable of being used together, have different modes of operation, different functions or different effects.
Adding to the complexity is that a single patent often includes claims for a method or process of making something as well as claims for the apparatus or object made by the process or utilizing the process. An example of a process and apparatus being related (not independent) inventions is if the process can be used only by the apparatus or can be used only to make the apparatus.
If it is determined that the inventions claimed within the patent application are not independent, i.e., related inventions, then the inventions must be analyzed for distinctiveness. (To muddle the matter further, the MPEP appears to use the term “patentably distinct” to describe both independent inventions and dependent inventions that are distinct.) Two inventions may be related but distinct if one is not obvious in relation to the other. Recall that novelty, utility and non-obviousness are the three essential elements of a patentable invention. Obviousness is separately discussed within this web site.
Basically a patent examiner should not hold two related inventions distinct unless the examiner is prepared to approve two separate patents if the elements of novelty and utility can be demonstrated.
If a patent application discloses two (or more) patentably distinct inventions, i.e., two independent inventions or two related inventions that are not obvious variations of the other, then the patent examiner may issue a “restriction”. A restriction requires the applicant or inventor to “elect” one of the two or multiple inventions for examination and prosecution. The non-elected claims may be either cancelled or merely withdrawn. The applicant is entitled to file a separate patent application, and pay a separate patent application fee, to prosecute the non-elected invention. This second application is termed a “divisional application”. It is entitled to the same priority date as the original or parent application. Understand that at this stage, the parent application only contains claims to the elected invention.
The examiner is supposed to give reasons (not a mere conclusion) justifying the restriction requirement, i.e., the determination that the application discloses two or more patentably distinct inventions and forcing the applicant to elect among the these inventions. This should allow the applicant to determine whether to object to the restriction requirement and preserve his/her rights. Whether or not the applicant objects (“traverses”) the restriction, the applicant is still required to make an election.
This brief article only begins the discussion of this topic. However, a restriction requirement may be the first action the applicant receives from the patent examiner. It will precede the examiner having made any search of the prior art. It may cause the applicant to make concessions regarding the invention(s) that may later be regretted (keeping in mind Festo and prosecution history estoppel).
Small comfort can be had in the USPTO conceding that the analysis or test of “patentably distinct” is “puzzling” and that only examiners having a requisite level of seniority and authority are permitted to issue restrictions.