l. A reissue patent must be for the same invention as the
original patent. R.S. § 4916. P. 315 U. S.
2. Original Patent No. 1,998,878, to Lefort, for a process for
the production of ethylene oxide, called for the introduction into
a heated reaction chamber of ethylene and oxygen, in the presence
of a catalyzer, and also, as an essential, the voluntary
introduction of water. Reissue Patent No. 20,370, in describing the
process, treats the voluntary introduction of water as permissive,
but not mandatory. Held,
that the reissue is void. P.
315 U. S.
3. Although it is the duty of a court to determine for itself,
by examination of the original and the reissue, whether they are
for the same invention, it is permissible, and often necessary, to
receive expert evidence to ascertain the meaning of a technical or
scientific term or term of art, so that the court may be aided in
understanding not what the instruments mean, but what they actually
say. P. 315 U. S.
4. It is inadmissible to enlarge the scope of the original
patent by recourse to expert testimony to the effect that a process
described and claimed in the reissue, different from that described
and claimed in the original patent, is, because equally
efficacious, in substance that claimed originally. P. 315 U. S.
5. The omission from a reissue patent of one of the steps or
elements prescribed in the original, thus broadening the claims to
cover a new and different combination, renders the reissue void,
even though the result attained is the same as that brought about
by following the process claimed in the original patent. P.
315 U. S.
121 F.2d 665 reversed.
Certiorari, 314 U.S. 603, to review the affirmance of a decree
of the District Court upholding a reissue patent in a suit for
Page 315 U. S. 669
MR. JUSTICE ROBERTS delivered the opinion of the Court.
This is a suit by the respondent to restrain the petitioner from
infringing claims 8 and 9 of reissue patent No. 20,370. The
application for reissue was filed September 25, 1936, and granted
May 18, 1937. The original patent was No. 1,998,878, applied for
March 22, 1932, and granted April 23, 1935, to Theodore Emile
Lefort of Paris, France, for a "Process for the Production of
Ethylene Oxide." The application was based on earlier French
patents. The respondent purchased the United States patent in April
1936, and, as a result of its study thereof, the patentee was
persuaded to apply for the reissue.
If the reissue patent is valid, no question is now raised as to
petitioner's infringement of the claims in suit. The District Court
held the patent valid and infringed. [Footnote 1
] The Circuit Court of Appeals affirmed.
] We took the case
because of an apparent conflict with decisions of this court and
several Circuit Courts of Appeals, to the effect that a reissue
patent must, under the statute, be for the
Page 315 U. S. 670
same invention as the original patent. [Footnote 3
] The petitioner also raised a question as to
intervening rights which, in the view we take, need not be
considered or decided.
Ethylene is a hydrocarbon gas, C2H4. For a long time, it was
thought impossible directly to oxygenize it to form C2H4O by
bringing oxygen and ethylene into contact, though the formation of
ethylene oxide by direct oxidation was commercially desirable.
Efforts at direct oxidation, instead of producing the oxide,
resulted in less desirable oxygenated compounds such as aldehydes.
Lefort conceived the idea of effecting the oxidation by catalytic
reaction -- that is, the use of a substance, which, in some
unexplained way, causes a chemical union or reaction when the two
substances to be affected are brought into contact in its presence
under given conditions. He recognized one incident of the direct
oxidation process as applied to ethylene tending to decrease its
efficiency -- namely, that, in addition to the principal reaction
producing C2H4O, there occurs a side reaction by which a portion of
the ethylene is converted into carbon dioxide and water, and, to
that extent, the ethylene is wasted. He found that, by certain
control of the process, this side reaction could be so restricted
as not to decrease the production of ethylene oxide below a
According to both the original patent and the reissue, ethylene
and oxygen are to be introduced into a heated reaction chamber in
the presence of a catalyzer. The petitioner insists that the
original patent also treats as
Page 315 U. S. 671
a mandatory or necessary step the voluntary introduction of
water, whereas the reissue in specification and claims 8 and 9
omits this requirement, and therefore describes a different
process. The respondent, on the other hand, asserts that, as both
patents describe the oxygen of air as that which may be used, and
as atmospheric air contains moisture, the first, specifying water,
and the reissue specifying air, both contemplate the introduction
of water in some form, and therefore are for the same process.
] This dispute must
be resolved by a comparison of the disclosures of the two
instruments. If that comparison leads to the conclusion that the
reissue is not for the same invention as the original, the reissue
is void as not within the terms of the statute.
We shall postpone discussion of the tests of identity or
difference of invention, and the use of expert testimony, to a
statement of the criteria of judgment furnished by the language of
the specifications and claims of the two documents.
The opening paragraph of the original patent is:
"This invention has for object a process for the production of
ethylene oxide, which mainly consists in subjecting ethylene to the
simultaneous action of the oxygen of air and of water in presence
of a catalyzer and, if need be, of hydrogen."
After referring to the use of hydrogen as optional, the
specification deals with the character and composition of metals to
be used as catalyzers. It then speaks of the elements to be used to
obtain the desired reaction thus:
Page 315 U. S. 672
"The ethylene can be obtained from any source of supply: . .
"Water can be admitted to the reaction vessel, either in the
liquid state, or as steam."
"The oxygen can be the oxygen of the air, this latter gas being
introduced in the reaction."
Immediately following, it is said:
"The efficiency of the reaction is increased by diminishing the
CO2 which is formed, by introduction, in this reaction, of a
suitable quantity of water. A suitable quantity of CO2 can also be
previously introduced in the reacting gases."
The CO2 which it is desired to diminish is that which is formed
by the undesirable side reaction above mentioned. This reaction is
again mentioned, and the introduction of water again specified
"Moreover, the applicant has found that the reaction giving CO2
is, contrarily to previous belief, a reaction of oxidation
independent from that giving ethylene oxide and from that giving
aldehydes. From experiments effected by the applicant, it results
that, if water is introduced in suitable quantity, the reaction is
not only facilitated, as above stated, but, in addition, the
reaction giving CO2, probably by direct oxidation of ethylene
according to the equation:"
"C2H4+3O2 = 2H2O+2CO2"
"is checked, owing, as is probable, to the partial pressure of
It is further said that the experiments indicate that the side
reaction producing CO2 and water may be completely checked and the
efficiency of the reaction producing ethylene oxide increased if
CO2 is previously introduced in addition to the water and the
Three modi operandi
are next indicated as examples. In
the first, compressed ethylene and compressed air are led, with or
without hydrogen, into a heated tube containing
Page 315 U. S. 673
the catalyzer, the tube being connected with a circulating pump
to supply water under pressure. In the second, the catalyzer is
introduced and the tube heated, and then "a mixture of ethylene,
air, water vapor and hydrogen" is sent through the tube. In the
third, the catalyzer is introduced into a high-pressure tube filled
with water. Pure ethylene is added "in order that it can dissolve
in the water." The tube is heated, and "air and hydrogen are slowly
The specification concludes:
"The experiments . . . have shown that, in presence of the
catalyzers indicated, water, in the form of steam or not,
considerably promotes the reaction ensuring the production of
All of the seven claims include oxygen and water or steam. Claim
1 is typical. It runs:
"A process for the production of ethylene oxide, consisting in
subjecting ethylene to the simultaneous action of oxygen and water,
in presence of a catalyst [describing the catalyst] at a
temperature between 150� and 400� C."
In some of the claims the word "steam" is substituted for
"water;" in two, "hydrogen" is added.
Various options or alternatives are mentioned in the
specifications, but nowhere in them, or in the claims, is the
introduction of water treated as optional or permissive. The
District Court made no finding directed to this fact, but the court
below definitely holds, and we agree, that, in the process defined
in the original patent, the voluntary introduction of water into
the reaction chamber is mandatory.
Experiments conducted by the respondent just before it acquired
the patent demonstrated that ethylene oxide could be produced by
passing ethylene and air over a catalyst at the temperature
described in the patent without the voluntary introduction of
water. Its patent attorney was asked to study the patent, and he
concluded that Lefort
Page 315 U. S. 674
should have obtained far broader claims. He prepared two oaths
for execution by Lefort to support the application for reissue.
In the first, it was averred that the specification and claims
failed to emphasize the fact that the reaction takes place "whether
or not water is present," and that the attorney, in drawing the
application, had not been adequately instructed that the "fullest
benefit and application" of the invention was the production of the
oxide in the presence of the catalyst "with or without the
inclusion of water in the reaction."
After rejection, the second affidavit was filed. This stated
that a certain amount of water was necessarily present in the
reaction chamber due to the side reaction which gives CO2 and
water, and that the introduction of additional water and carbon
dioxide was merely permissive, in order to augment the quantities
already formed by that reaction.
Thereupon, reissue was granted with a rewritten specification,
the seven original claims and two new ones, 8 and 9, which are
those in suit.
The substituted specification opens thus:
"This invention provides a specific and novel process for making
ethylene oxide. It essentially consists in causing ethylene to
combine directly with molecular oxygen at temperatures of about
150� to about 400� C. in the presence of a surface catalyst which
favors the oxidation of ethylene to ethylene oxide under these
The statement is made that ethylene from any source can be used,
and that the oxygen can be that of the air.
The only reference to the introduction of water is:
"The oxidation of ethylene takes place with a giving off of
heat, and it is, of course, desirable to maintain the temperature
of the zone of reaction within the range specified. This can be
facilitated by suitable dilution of the reaction
Page 315 U. S. 675
gases, such as that accomplished by the use of air as the source
of oxygen, and some water or carbon dioxide in addition to that
formed can be admitted to the mixture in the reaction zone if
desired. Hydrogen may be similarly added."
The description of the mode of conducting the process differs
from all those given in the original specification in omitting the
introduction of water.
The specification concludes:
"In any case, the ethylene and oxygen are thus reacted
simultaneously at the temperatures set forth in the presence of a
surface catalyst and of water."
The new claims 8 and 9 are broader than those of the original
patent. [Footnote 5
] It will
suffice to quote 8. It is:
"The process of making ethylene oxide by the direct chemical
combination of oxygen with ethylene in the proportions of one atom
of oxygen to one molecule of ethylene, which comprises forming a
mixture containing ethylene and molecular oxygen and conducting
said mixture through a confined reaction zone which is maintained
at an elevated temperature; controlling said temperature to
maintain said mixture in said zone at a temperature between about
150� and about 400� C; subjecting said mixture in said zone at said
elevated controlled temperature to intimate contact with an active
describing it, inter alia,
as one which favors the
formation of "oxidation products containing ethylene oxide in the
presence of water," and describing other steps not necessary to be
The question is whether, in the light of the disclosures
contained in the two patents, they are for the same invention. This
court has said that they are if the reissue
Page 315 U. S. 676
fully describes and claims the very invention intended to be
secured by the original patent; [Footnote 6
] if the reissue describes and claims only those
things which were embraced in the invention intended to have been
secured by the original patent; [Footnote 7
] if the broader claims in the reissue are not
merely suggested or indicated in the original specification, but
constitute parts or portions of the invention which were intended
or sought to be covered or secured by the original patent.
] The required
intention does not appear if the additional matter covered by the
claims of the reissue is not disclosed in the original patent.
] If there be
failure of disclosure in the original patent of matter claimed in
the reissue, it will not aid the patentee that the new matter
covered by the reissue was within his knowledge when he applied for
his original patent. [Footnote
] And it is not enough that an invention might have been
claimed in the original patent because it was suggested or
indicated in the specification. It must appear from the face of the
instrument that what is covered by the reissue was intended to have
been covered and secured by the original. [Footnote 11
As the Circuit Court of Appeals held, the original specification
and claims treated the voluntary introduction of water into the
reaction chamber as a necessary step in the
Page 315 U. S. 677
process, whereas such introduction is made permissive by the
reissue. We agree with that court's view that there is thus a
difference between the procedure described in the two documents.
But we cannot agree with its conclusion that the difference is so
insubstantial as not to invalidate the new claims 8 and 9. On the
face of the papers, the process described in the original patent
included a step not designated as optional or desirable, but
described and claimed as an integral part of the whole operation.
In contrast, the reissue treats this step as immaterial, and
mentions the introduction of water as for the mere purpose of
controlling the temperature in the reaction zone -- a thought not
even suggested by the specification of the original patent, which,
on the contrary, in its very first sentence, speaks of the
simultaneous action of the oxygen of air and of water.
We think it plain that the reissue omitted a step in the process
which was described and claimed as essential in the original
patent. The court below was persuaded by expert testimony that,
from a chemist's point of view, the prescribed step (the
introduction of water) was immaterial; in other words, chemists
testified that, by carrying out the procedure, omitting the
introduction of water, they obtained the results described in the
patent. Naturally enough, this fact led them to state, as chemists,
that the introduction of the water was immaterial. Apparently this
testimony induced both of the courts below to conclude that Lefort,
when he applied for his original patent, knew that the introduction
of water was unnecessary. The inquiry at once arises, if this were
so, why did he not say so. If he had discovered a process, which
the claims of the reissue are certainly broad enough to cover --
that of mixing dry oxygen and ethylene in the presence of a
catalyst at the prescribed temperature to produce ethylene oxide --
it is not understood why, throughout his
Page 315 U. S. 678
specifications and claims, he spoke of exposing ethylene to the
simultaneous action of oxygen and water or steam.
We think the court below fell into error in adopting the
scientific conclusion of expert witnesses that the result would be
the same whether water were introduced into the reaction chamber or
not as proof that Lefort's invention was not what he stated it to
be in his original patent, but rather the invention of a process of
bringing ethylene and oxygen into contact in the presence of a
Although it is the duty of a court to determine for itself, by
examination of the original and the reissue, whether they are for
the same invention, it is permissible, and often necessary, to
receive expert evidence to ascertain the meaning of a technical or
scientific term or term of art so that the court may be aided in
understanding not what the instruments mean, but what they actually
say. [Footnote 12
] It is
inadmissible to enlarge the scope of the original patent by
recourse to expert testimony to the effect that a process described
and claimed in the reissue, different from that described and
claimed in the original patent, is, because equally efficacious, in
substance that claimed originally. [Footnote 13
] If such testimony could tip the scales on
the issue of the validity of a reissue, it would always be possible
to substitute any new combination of steps or elements or devices
for the one originally described and claimed by proving that the
omission of any one or more steps would not alter the result.
This court has uniformly held that the omission from a reissue
patent of one of the steps or elements prescribed in the original,
thus broadening the claims to cover a new and different
combination, renders the reissue void, even though the result
attained is the same as that brought about by following the process
claimed in the original patent.
Page 315 U. S. 679
In Russell v. Dodge, 93 U. S. 460
93 U. S. 464
the original patent was for treating skins by the use of a compound
in which heated fat liquor was expressly stated as an essential
ingredient. There was no disclosure that the fat liquor could be
used cold. In a reissue, the specification was altered by
eliminating the requirement that the liquor be heated. The court
"The change made in the old specification, by eliminating the
necessity of using the fat liquor in a heated condition and making
in the new specification its use in that condition a mere matter of
convenience, and the insertion of an independent claim for the use
of fat liquor in the treatment of leather generally, operated to
enlarge the character and scope of the invention. The evident
object of the patentee in seeking a reissue was not to correct any
defects in specification or claim, but to change both, and thus
obtain, in fact a patent for a different invention. This result the
law, as we have seen, does not permit."
In Gill v. Wells,
22 Wall. 1, the original patent disclosed and claimed a machine for
making hat bodies. One of the elements of the machine was a tunnel
through which a current of air was to be passed. The specifications
did not indicate that this part could be omitted. The reissue for a
machine without any tunnel was held invalid. The court said (p.
89 U. S. 26
"Argument to show that an invention consisting of a combination
of three ingredients which are old is not the same as that of a
combination of four old ingredients is quite unnecessary, as the
negative of the proposition is as well settled in the patent law as
it is in mathematics."
Many other cases might be cited to the same effect.
The court below was persuaded to construe the reissue patent as
not differing from the original by the argument that, in both, the
introduction of water was not essential to the technological
success of the process. When certiorari was applied for in this
court, the respondent, in its
Page 315 U. S. 680
"The introduction of water, as distinguished from its presence,
in the reaction zone is not 'an essential feature' in the invention
at bar, and was not 'described and claimed in the original patent
as an essential feature.'"
This argument goes upon the theory that, if the presence of
water is necessary to the reaction, its presence is assured by the
side reaction we have mentioned which produces CO2 and water. It
does not explain, however, why, if this is the source of the
necessary water, Lefort did not say so in his original patent. Nor
does it suggest how the reaction can be initiated or caused when
dry oxygen is used and the side reaction has not commenced.
In the argument on the merits in this Court, the respondent
shifted its position. In brief and argument, it stated that both
the original and reissue cover the same invention, for, if both
require the introduction of water, the described introduction of
air effects also the introduction of water, since atmospheric air
contains both oxygen and moisture. It is thus sought to avoid the
finding of the Circuit Court of Appeals that the original patent
called for the voluntary introduction of water, and the reissue
does not. This argument fails to square with the specification or
claims of either the original patent or the reissue. The claims of
the original patent are not limited to the oxygen of air, and the
specification merely says the oxygen "can be the oxygen of air."
The specification and claims of the reissue are satisfied by the
introduction of dry oxygen.
In short, to avoid the difficulties which stare one in the face
when the attempt is made to read specifications and claims as
calling for the same process, the respondent is driven to take
inconsistent positions, neither of which comports with the plain
language of the two patents.
Page 315 U. S. 681
We hold that the reissue is not for the same invention described
and claimed and intended to be secured by the original patent, and
is therefore void.
The decree is
34 F. Supp. 813.
121 F.2d 665.
R.S. § 4916, 35 U.S.C. § 64:
"Whenever any patent is wholly or partially inoperative or
invalid, by reason of a defective or insufficient specification, or
by reason of the patentee claiming as his own invention or
discovery more than he had a right to claim as new, if the error
has arisen by inadvertence, accident, or mistake, and without any
fraudulent or deceptive intention, the Commissioner shall . . .
cause a patent for the same invention,
and in accordance
with the corrected specification, to be reissued. . . ."
No question of unreasonable delay is presented. Compare Mahn
v. Harwood, 112 U. S. 354
112 U. S. 363
Ives v. Sargent, 119 U. S. 652
119 U. S. 661
Topliff v. Topliff, 145 U. S. 156
145 U. S. 169
Nor have we occasion to decide what may be the scope of permissible
court review of the commissioner's determination that the error of
the patentee arose "by inadvertence, accident or mistake, without
fraudulent or deceptive intention."
This fact, standing alone, does not vitiate the reissue.
Topliff v. Topliff, 145 U. S. 156
Giant Powder Co. v. California Powder Works,
98 U. S. 126
98 U. S.
Parker & Whipple Co. v. Yale Clock Co.,
123 U. S. 87
123 U. S. 99
Hoskin v. Fisher, 125 U. S. 217
125 U. S. 223
Flower v. Detroit, 127 U. S. 563
127 U. S.
Corbin Cabinet Lock Co. v. Eagle Lock Co., 150 U. S.
, 150 U. S.
Clements v. Odorless Excavating Apparatus Co.,
109 U. S. 641
109 U. S. 647
Coon v. Wilson, 113 U. S. 268
113 U. S. 277
Electric Gas Lighting Co. v. Boston Electric Co.,
139 U. S. 481
139 U. S. 501
Freeman v. Asmus, 145 U. S. 226
145 U. S. 239
Olin v. Timken, 155 U. S. 141
155 U. S.
Giant Powder Co. v. California Powder Works, supra,
98 U. S. 138
Swain Turbine & Manufacturing Co. v. Ladd,
102 U. S. 408
102 U. S. 413
Huber v. Nelson Mfg. Co., 148 U.
Parker & Whipple Co. v. Yale Clock Co., supra; Flower v.
11 Wall. 516, 78 U. S.
Union Paper Collar Co. v. Van
23 Wall. 530, 90 U. S.