6a) The law relating to opposition, re-examination and/or revocation of granted US patents

Question 1

Discuss the doctrine of equivalents.

Answer 1

• Typically related to infringement actions.
• The patented invention is defined by the claims for the purpose of determining literal
infringement, i.e. claim wording must read on alleged infringement.
• Alternatively, infringement may be found under the “doctrine of equivalents”: prevents
copying of invention whilst avoiding literal claim language.

Question 2

Discuss file wrapper estoppel.

Answer 2

• However, the extent of the doctrine of equivalents is limited by file wrapper estoppel which
essentially means that the patentee is precluded from recapturing scope of claim
previously surrendered by an amendment or a remark made during prosecution. The file
wrapper consists of all papers filed at USPTO during prosecution. In addition, statement
made in prosecution a corresponding application or patent in a non-US country can be
cited in US litigation and deemed to affect the interpretation of US patent.
• The effect of this is that it is advantageous to get claims granted that have not been
amended during prosecution. This limits the effect of the file wrapper and may allow for a
broader claim interpretation under the “doctrine of equivalents”. This was shown in the US
Supreme case Festo and is why you often see lots of independent claims in the US with
very similar scope. The hope is that some will go through without amendment or any
arguments being put on the file.

Question 3

Discuss re-issue

Answer 3

• Re-issue allows an applicant to change the scope of their patent post grant. It is not available to
3rd parties. This can be used if:
o There is a defect in the specification, claims or drawings;
o Patent claims more/less than they can (note this allows for claim broadening after grant –
c.f. Europe).
• Claims can be narrowed using re-issue procedures at any stage. However, claim broadening
must occur within two years of the grant date.
• On request of the applicant, the commissioner shall, on surrender of the patent and payment of
the fee, re-issue the patent for the unexpired part of the original term. Claims or subject matter
cancelled during original prosecution cannot be revived.
• Application is examined in its entirety and resulting file wrapper will be made available for public
inspection. Therefore, the danger with re-issue is that second time round, the patent gets
refused or new arguments are presented against the claims which adversely affects the
patentee.

Question 4

Discuss post-grant review

Answer 4

• Within nine months of grant a third party can request post-grant review of a patent and
thereby cancellation of one or more claims on the grounds of novelty, obviousness, written
description, enablement, statutory subject matter and double patenting and on the basis of
any type of evidence.
• Accordingly, the grounds for review are more numerous, and the evidence that may be
used more extensive, than under the current re-examination procedure and so the new
system is more akin to the EPO’s opposition procedure.
• This procedure only applies to patents granted from patent applications filed after 16 March
2013.

• Unlike the EPO opposition procedure however, the USPTO will only initiate full review
proceedings if it determines that the petition demonstrates that “it is more likely than not
that at least one of the claims challenged in the petition is un-patentable” or if the petition
“raises a novel or unsettled legal question that is important to other patents or patent
applications”.
• Any decision to refuse initiation of proceedings is final and not appealable
• A notable feature of these post-grant review provisions, however, is that the petitioner is
estopped from raising the same issues, and issues that reasonably could have been
raised, in subsequent court proceedings and future inter parties reviews.

Question 5

Discuss inter-partes review

Answer 5

• After the period for requesting post-grant review, or the termination of any post-grant
review of a patent, a third party may, under the new inter parties review procedure, at any
time request cancellation of one or more claims of a patent granted on or after 16
September 2012 on the grounds of novelty and obviousness on the basis of printed
publications.
• Thus, although there are less time restrictions on inter parties review, the scope of the
review is much more curtailed than post grant review. The USPTO will, however, only
initiate the inter parties review if the petitioner can show that he is “reasonably likely to
prevail with respect to at least one of the claims being challenged”.
• The USPTO clarified on 18 August 2020 that an inter-partes review can’t be initiated
exclusively based on applicant-admitted prior art, but that statements from the specification
of a patent can be used to inform decisions about obviousness and the common general
knowledge.

• This is a higher threshold than that applied traditionally in inter parties re-examination. The
same estoppels as for post-grant review apply to inter parties review.
• The majority of patents which have been the subject of inter parties review have been
invalidated, therefore, many companies are looking at this as a lower cost route to
invalidating patents compared with litigation.
• IPR is a popular pathway. One reason is the Patent trial and appeal boards (PTAB’s) use of the broadest reasonable
interpretation (BRI) standard for construing patent claims. PTAB reviews patentability
under a “preponderance of the evidence” standard rather than the higher “clear and
convincing evidence” used in the US district courts.

Question 6

Discuss supplemental examination.

Answer 6

• Lastly, under the supplemental examination provisions of the new Act, patentees are able
to have the USPTO “consider, reconsider or correct information believed to be relevant to
the validity of a patent” after the patent has been granted.
• If the request is filed before proceedings against the patent are initiated by a third party, or
if the supplemental examination is completed before the patent is enforced, allegations of
inequitable conduct cannot be made on the basis of the matters dealt with in the
supplemental examination.
• Unlike the current re-examination system, the remit of this examination is not restricted to
issues of novelty and inventive step and is not based solely on printed publications.