We tend to think of the grant of a patent as establishing a set body
of rights, in the form of claims that continue in force and unchanged
throughout the term of the patent. Most of the time, that's exactly
what happens. However, there are circumstances in which the claims of
a patent, as granted, are not the last word on what might, or might
not, infringe the patent.
The law allows the establishment of "intervening rights," or rights
that would otherwise infringe issued patents, under three very
specific circumstances. These circumstances arise when the scope of a
patent is changed by either reissue or reexamination, or where a
patent is revived after failure to pay a maintenance fee. The concept
is one of fairness; if the claims of a patent change in scope or
enforceability, it would be fair to allow practices that might
otherwise be infringements, because the so-called infringers had no
way of firmly predicting the final scope of the patent claims.
All of these "intervening rights" are provided by explicit statutes.
In the reissue statute, 35 U.S.C. S 252, two types of intervening
rights are established. In a reissue, the grantee asks the patent
office to allow the additional claiming of material that while
supported in the original disclosure, was defectively specified or
claimed, or inadvertently not claimed. As a result, new claims,
granting new and broader scope, may be added to the patent.
To protect those who might, in good faith, have relied on the original
grant of the patent to delineate the bounds of its claims, absolute
intervening rights are granted to those who, "prior to the grant of a
reissue, made, purchased, offered to sell, or used unless such thing
infringes a valid claim of the reissued patent which was in the
original patent." Such intervening rights are mandatory upon the
court, as indicated by the language "a reissued patent shall not
A second class of intervening rights, equitable intervening rights, is
extended even to those who made "substantial preparation" to practice
an aspect of the invention later barred by a new claim in the reissue.
These equitable intervening rights are within the discretion of the
court, which by statutory language is instructed, "The court before
which such matter is in question may provide " The difference between
absolute and equitable rights can be important in an infringement
defense. Equitable rights, the weaker of the two, are an affirmative
defense and are waived if not pleaded, or at least raised, at trial
during the liability phase of the suit. On the other hand, failure to
raise the issue of absolute intervening rights is not a waiver of
those rights, which can be raised even after the liability phase has
In the second situation where intervening rights may be established,
35 U.S.C. S 307(b) provides for intervening rights following
reexamination. A reexamination re-opens a patent to new scrutiny by
the patent office, and existing claims may be lost, or new claims
approved. If a claim is amended, or a new claim allowed, the effect is
similar to that of a reissue patent. Absolute rights are granted to
those actually practicing an activity infringing a new claim, while
equitable rights are granted to those who may have made "substantial
preparations" to do so.
The last situation where intervening rights may be established is
following a successful petition to accept a late maintenance fee that
was unavoidably or inadvertently not paid. A patent holder normally
has six months following the due date for a maintenance fee to have
the required fee to the patent office, or the patent will be deemed
abandoned and its teaching will pass into the public domain. (See "Pay
Those Maintenance Fees" in last month's newsletter at
www.invention-protection.com) If the patent holder can convince the
Commissioner, within 24 months following the abandonment of the
patent, that the failure to pay the maintenance fee was either
unavoidable or inadvertent, the Commissioner may order the patent
reinstated. In order to protect those who relied on the presumptive
abandonment of the patent, absolute and equitable intervening rights
are again allowed. Absolute rights are extended to those who actually
practiced the patent during the period of abandonment, while equitable
rights "may" be extended to those who made "substantial preparation"
to do so. These rights are limited to the period beginning after the
six month grace period after the maintenance fee due date up to the
date that the Commissioner actually accepts the delayed maintenance
fee and grants the petition.
This doctrine of "intervening rights" essentially allows one to rely
on patents as issued or as abandoned, such that later changes in scope
or petitions to revive abandoned patents do not unfairly impact good
faith, but technical, "infringers."