Issues regarding consonance between restricted claims and double patenting problems seem to come up mostly in litigated pharmaceutical patents. The issue also arises sometimes in divisional applications where the examiner inters a double patenting rejection. But, the issue may not be on the radar in every day prosecution when the first action restriction is issued, although it should be.
First it may be helpful to review the basic issues. A divisional patent application resulting from an Examiner-imposed restriction requirement cannot later be rejected on the grounds of nonstatutory obviousness-type double-patenting in light of the parent application pursuant to the safe harbor provisions of 35 U.S.C. § 121. However, with regard to double patenting, § 121 will not apply to remove the parent as a reference where the principle of consonance is violated. Consonance requires that the line of demarcation between the "independent and distinct inventions" that prompted the restriction requirement be maintained. Though the claims may be amended, they must not be so amended as to bring them back over the line imposed in the restriction requirement. Where that line is crossed the prohibition of the third sentence of Section 121 does not apply. Symbol Technologies, Inc. v. Opticon, Inc., 935 F.2d 1569, 1579 (Fed. Cir. 1991); see also Gerber Garment Technology Inc. v. Lectra Systems Inc., 916 F.2d 683, 688 (Fed. Cir. 1990).
So how is this relevant to that first Office action restriction? Because the USPTO cannot have it both ways. If an examiner restricts an application, the applicant might sometimes consider amending the claims to purposely violate the principle of consonance and then argues that the claims should be examined and the restriction withdrawn. Further, even if the applicant is unsuccessful, such prosecution history might be extremely valuable later-on to defend against a double-patenting attack.
An example of how to amend claims to purposely violate consonance is illustrated in a recent PTAB decision (SN 14/594,313). Here, the approach is quite easy - just amend the elected claims to include some features from the un-elected claims. As the PTAB noted in the above case:
Specifically, the Examiner sufficiently illustrates loss of consonance between original claim 16 and amended claim 16 - invention II (similarly original claim 1 and divisional claim 1 - invention I) in the charts represented in the Answer (see Ans. 14--19). For example, amended claim 16 was amended by incorporating limitations from non-elected claim 1, i.e., "measure a spectral composition of the optical output signal over one or more wavelength ranges ... adjust a spectral location of optical pass bands ... "(see Ans. 15-17)(emphasis added). As a result, the line of demarcation between the "independent and distinct inventions" that prompted the restriction requirement was not maintained between invention I and invention II. Specifically, invention II can no longer be practiced without measuring spectral intensities and measuring the output over one or more wavelength ranges, i.e., the Examiner's reason for making the restriction requirement (see Ans. 15).
It should be noted that the PTAB affirmed the double patenting rejection even though the PTAB seemed to agree that the claims of the present divisional application include all the limitations of the originally restricted claims and were only narrowed during prosecution. Therefore, the Appellants argued that if original claim 16 was distinct from original claim 1, an d both claims were similarly narrowed by amendment, then amended claims 16 and 1 remain distinct from each other, i.e., "the narrowed Inventions I and II are also distinct from each other". However, for the reasons noted above, the PTAB disagreed.
While the PTAB’s reasoning may have some holes, it nevertheless is a common approach at the USPTO. Thus, applicants hoping to avoid or minimize restrictions in the first place might consider amendment and petition strategies taking into account the issue of consonance.