Swiss Patent Attorney practice questions

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Question 1Patent law (national and international)

Under the Swiss Patents Act, what is the maximum term of a Swiss patent, counted from the filing date?

20 years Correct answer.
15 years
25 years
10 years

Explanation

Article 14 of the Swiss Patents Act sets the maximum patent term at 20 years from the filing date. This aligns with the minimum term required by the TRIPS Agreement and the European Patent Convention. Supplementary protection certificates can extend protection for certain pharmaceuticals and plant protection products beyond that period.

Question 2Patent law (national and international)

Which authority grants Swiss patents and also acts as the receiving office for international applications filed by Swiss residents?

The Federal Supreme Court in Lausanne
The Federal Institute of Intellectual Property (IPI) in Bern Correct answer.
The Swiss Federal Institute of Technology in Zurich
The State Secretariat for Economic Affairs

Explanation

The Swiss Federal Institute of Intellectual Property (Eidgenössisches Institut für Geistiges Eigentum, IGE/IPI) is the national patent office. It examines national applications, grants Swiss patents and functions as a receiving office under the PCT. The Federal Supreme Court only reviews decisions on appeal, and the other bodies have no grant competence.

Question 3Patent law (national and international)

What is the decisive criterion for an invention to be patentable under Swiss law regarding technical character?

The invention must be presented as a physical prototype
The invention must solve a technical problem by technical means Correct answer.
The invention must be kept secret until grant
The invention must have commercial value in Switzerland

Explanation

Swiss practice, like EPO practice, requires an invention to have technical character: it must solve a technical problem using technical means. Purely aesthetic, economic or mental-rule solutions are excluded. Commercial value and prototypes are irrelevant to patentability.

Question 4Patent law (national and international)

Which document must be filed to claim priority from an earlier application under the Paris Convention when filing a Swiss national application?

Only an oral statement at the counter
A priority declaration identifying the earlier application, followed by a certified copy if requested Correct answer.
A notarised translation of the entire earlier application
A power of attorney signed by the inventor

Explanation

To claim priority, the applicant must declare the earlier application and its filing date and country within the prescribed period. The IPI may then require a certified copy of the priority document. An oral statement or a full notarised translation is not the prescribed route.

Question 5Patent law (national and international)

How long is the novelty grace period under Swiss law for disclosures by the applicant or their predecessor in title?

6 months preceding the filing or priority date Correct answer.
24 months preceding the filing or priority date
12 months preceding the filing or priority date
No grace period exists in Swiss law

Explanation

Article 7a of the Swiss Patents Act provides a six-month grace period for disclosures made by the applicant or their predecessor in title. This is shorter than the twelve-month grace period available in some other jurisdictions. Disclosures by third parties without authorisation are treated differently.

Question 6Patent law (national and international)

In Swiss patent infringement proceedings, which court has first-instance jurisdiction over a patent dispute?

The Federal Institute of Intellectual Property
An arbitral tribunal appointed by the IPI
The competent cantonal court designated for IP matters Correct answer.
The Federal Administrative Court

Explanation

Civil infringement actions are heard at first instance by the cantonal court designated by cantonal law for intellectual property disputes. The IPI is an administrative authority and does not decide infringement. The Federal Supreme Court hears appeals in civil patent matters.

Question 7Patent law (national and international)

What is the effect of a Swiss patent being declared null by a court?

The patent is converted into a utility model automatically
The patent is transferred to the Swiss Confederation
The patent is deemed never to have had effect, subject to protection of good-faith reliance under the applicable rules Correct answer.
The patent remains valid until the end of its term

Explanation

A declaration of nullity removes the patent with retroactive effect, meaning it is treated as never having existed. Swiss law and general principles protect certain good-faith positions, for example regarding acts already performed. Nullity is distinct from lapse for non-payment of fees.

Question 8Patent law (national and international)

Which international treaty established the right of priority for patent applications among member states?

The Berne Convention
The Madrid Agreement
The Paris Convention for the Protection of Industrial Property Correct answer.
The Vienna Convention on the Law of Treaties

Explanation

The Paris Convention, concluded in 1883, introduced the right of priority allowing an applicant to file in other member states within a set period while retaining the original filing date. The Berne Convention covers copyright, and the Madrid Agreement concerns trademarks.

Question 9Patent law (national and international)

A Swiss applicant files a European patent application at the EPO. Which statement best describes the relationship between that application and a later Swiss national filing for the same invention?

The later Swiss filing automatically invalidates the European application
The European application blocks any Swiss filing permanently
The European application can serve as a priority basis for the later Swiss filing within twelve months Correct answer.
The later Swiss filing must be filed on the same day as the European application

Explanation

A European patent application has the effect of a regular national filing and can serve as a priority basis under the Paris Convention. The later Swiss application must be filed within twelve months to benefit from the priority date. It does not invalidate the earlier application.

Question 10Patent law (national and international)

An examiner finds that a Swiss patent application claims a computer program as such. How should the applicant best respond to secure patentability?

Argue that the program is innovative and commercially successful
Request that the program be treated as a literary work
Frame the claim as a method producing a technical effect on a technical apparatus Correct answer.
Submit the source code as the sole description

Explanation

Computer programs as such are excluded, but a claimed method or device producing a technical effect is patentable. Framing the subject-matter around a technical apparatus or technical effect addresses the exclusion. Commercial success and source code alone do not overcome it.

Question 11Patent law (national and international)

A third party begins using an invention in Switzerland before the applicant files, without the applicant's authorisation, having independently derived it. Which statement reflects Swiss novelty law?

The prior use creates a joint patent right for the third party
The third party's use is irrelevant because only the applicant's own acts count
The third party's prior use destroys novelty because it is a public prior use Correct answer.
The prior use is excused only if the third party is a Swiss resident

Explanation

Any public prior use by a third party, whether authorised or not, forms part of the state of the art and destroys novelty. The grace period covers only disclosures by the applicant or their predecessor in title, not independent third-party disclosures. Joint rights do not arise from prior use.

Question 12Patent law (national and international)

What is the primary function of the claims in a Swiss patent specification?

They record the fees paid to the IPI
They describe the background of the invention only
They define the scope of protection sought and granted Correct answer.
They list the inventor's qualifications

Explanation

Under the Patents Act the claims define the scope of protection, while the description and drawings serve to interpret them. The claims must be clear and supported by the description. Background material and administrative data belong elsewhere.

Question 13Patent law (national and international)

A patentee discovers that a competitor is importing infringing goods into Switzerland. Which measure is available in civil proceedings?

An administrative appeal to the Federal Administrative Court
A request that the IPI revoke the competitor's business licence
A criminal complaint to the IPI requesting seizure of the patent
An action for injunction and damages before the competent cantonal court Correct answer.

Explanation

The patentee may bring a civil action before the designated cantonal court seeking an injunction, removal, damages and other remedies. The IPI does not seize goods on a criminal complaint, and the Federal Administrative Court does not hear infringement claims. Business licences are unrelated to patent enforcement.

Question 14Patent law (national and international)

Under the PCT, by when must an applicant file the demand for international preliminary examination?

Within 30 months from the priority date
Within 22 months from the priority date or 3 months from the transmittal of the search report, whichever is later Correct answer.
Within 12 months from the priority date
At any time before national phase entry

Explanation

The PCT sets the deadline for filing a demand for international preliminary examination at 22 months from the priority date or three months from transmittal of the international search report, whichever expires later. The 30-month period relates to national phase entry, not the demand.

Question 15Patent law (national and international)

An applicant wants to extend protection for a pharmaceutical product beyond the 20-year patent term in Switzerland. Which instrument applies?

A supplementary protection certificate granted under the applicable Swiss rules Correct answer.
A utility model registration
A design registration for the packaging
A trademark registration for the product name

Explanation

Supplementary protection certificates extend patent protection for medicinal products and plant protection products to compensate for regulatory approval time. Utility models, trademarks and designs protect different subject-matter and do not extend the patent term.

Question 16Patent law (national and international)

What does the principle of unity of invention require in a Swiss patent application?

The application must claim one single physical product
The application must be in one of the official languages only
The application must be filed by a single inventor
The application must relate to a single inventive concept or a group of linked inventive concepts Correct answer.

Explanation

Unity of invention requires that the application relate to one invention or to a group of inventions so linked as to form a single general inventive concept. It does not restrict the number of inventors, and language rules are a separate formal requirement.

Question 17Patent law (national and international)

A Swiss patent is granted but the annual renewal fee for a given year is not paid on time. What is the consequence if the fee remains unpaid after the applicable grace period?

The patent lapses with effect from the due date Correct answer.
The patent term is extended by one year
The patent is automatically transferred to the IPI
The patent becomes a trade secret

Explanation

Failure to pay the renewal fee within the prescribed period and any applicable grace period causes the patent to lapse. The lapse takes effect from the due date, and the patentee may seek restoration only under the specific statutory conditions. The IPI does not acquire the patent.

Question 18Patent law (national and international)

Which statement correctly describes the novelty requirement under Swiss law?

An invention is novel if no Swiss patent has previously been granted for it
An invention is novel if the applicant believes it has never been seen before
An invention is novel if it is not sold in Switzerland
An invention is novel if it does not form part of the state of the art, which comprises everything publicly available before the filing or priority date Correct answer.

Explanation

Novelty is assessed against the entire state of the art, meaning everything made available to the public before the relevant date anywhere in the world. Subjective belief, lack of sales in Switzerland or the absence of a prior Swiss patent are not the legal test.

Question 19Patent law (national and international)

An applicant files a Swiss patent application and later realises the description omits an essential feature needed for the claimed invention. What restriction applies to adding that feature after the filing date?

Amendments may be made freely until grant
Amendments may add any feature known in the art
Amendments may not extend beyond the content of the application as filed Correct answer.
Amendments may be made only after grant

Explanation

Swiss law prohibits amendments that extend the subject-matter beyond the disclosure of the application as filed, mirroring the EPC standard. This protects third parties and the priority basis. Adding an undisclosed essential feature would generally be inadmissible.

Question 20Patent law (national and international)

Which of the following is a recognised ground for invalidating a granted Swiss patent?

The patentee failed to market the invention in Switzerland
The patent was granted in a language other than the applicant's mother tongue
The claimed subject-matter lacked novelty over the prior art at the filing date Correct answer.
The patentee changed address without notifying the IPI

Explanation

Lack of novelty, lack of inventive step, insufficient disclosure, excluded subject-matter and added matter are classic nullity grounds. Failure to notify a change of address or to commercialise the invention does not invalidate a patent, and language of grant is not a nullity ground.

Question 21Patent law (national and international)

Under the EPC, what is the effect of a European patent granted for Switzerland after the opposition period expires without opposition?

It has the same effect in Switzerland as a national Swiss patent Correct answer.
It applies only if the patentee is resident in Switzerland
It requires a separate full re-examination by the IPI before it takes effect
It is automatically converted into a utility model

Explanation

A European patent designates Switzerland and, once granted, has the same effect as a national Swiss patent. No separate re-examination by the IPI is required, and residence of the patentee is irrelevant. National validation requirements, where applicable, are formal.

Question 22Patent law (national and international)

An employee develops an invention in the course of their employment under Swiss law. Who is entitled to apply for the patent in the absence of a contractual agreement?

The employer, provided the invention arose in the performance of the employment relationship and the employer claims it Correct answer.
The IPI, which allocates the right
The employee exclusively, with no possibility of transfer
The employee and employer jointly by operation of law

Explanation

Under the Swiss employment-invention regime, inventions made in the performance of employment duties and not covered by a special agreement belong to the employer if the employer claims them. The employee is entitled to compensation where appropriate. Joint ownership does not arise automatically.

Question 23Patent law (national and international)

A patentee wishes to rely on a prior-user right against an alleged infringer in Switzerland. Which condition is essential?

The user had published the invention before the filing date
The user holds a later Swiss patent on the same invention
The user is a public research institution
The user began or made serious preparations to use the invention in good faith before the filing or priority date Correct answer.

Explanation

Swiss law recognises a prior-user right where a person, in good faith, began using the invention or made serious preparations before the filing or priority date. The right is limited to the scope of that use. Publication before filing would instead destroy novelty, and holding a later patent does not create a prior-user right.

Question 24Patent law (national and international)

An examiner objects that a claim is not sufficiently disclosed. What is the correct legal focus of the analysis?

Whether the invention has been published in a peer-reviewed journal
Whether the claim language is shorter than the description
Whether the description enables a person skilled in the art to carry out the claimed invention across the scope claimed Correct answer.
Whether the applicant has included a working prototype

Explanation

Sufficiency of disclosure requires that the description enable the skilled person to carry out the invention over the whole scope claimed, without undue burden. A prototype or peer-reviewed publication is not the legal standard. Claim length has no bearing on enablement.

Question 25Patent law (national and international)

A Swiss patent claims a selection of individual compounds from a broad prior-art genus. Which test best determines whether the selection is novel?

The selection is novel if the compounds are easy to synthesise
The selection must be distinguished from the prior art by a purposive selection producing a technical effect across the whole claimed range Correct answer.
The selection is novel if the number of compounds is small
The selection is novel if the applicant names the compounds in the title

Explanation

For a selection from a broad genus to be novel, the selected members must not have been individualised in the prior art and the selection must be purposive, producing a technical effect across the claimed range. The mere number of compounds or ease of synthesis is not the test.

Question 26Patent law (national and international)

Which body performs substantive examination of national Swiss patent applications?

The Federal Patent Court
The Swiss Federal Institute of Intellectual Property Correct answer.
The European Patent Office
The World Intellectual Property Organization

Explanation

The Swiss Federal Institute of Intellectual Property (IPI) is the national office that receives and examines Swiss patent applications. The EPO handles European applications, the Federal Patent Court adjudicates civil disputes, and WIPO administers international treaties.

Question 27Patent law (national and international)

Which document of a Swiss patent application defines the scope of protection sought?

The drawings
The claims Correct answer.
The description
The abstract

Explanation

The claims determine the scope of protection, while the description and drawings serve to interpret them. The abstract is only a technical search aid and has no legal effect on scope.

Question 28Patent law (national and international)

A Swiss patent application is filed on 3 March 2023. By what date must the applicant generally pay the annual renewal fee for the third patent year?

By the last day of the month preceding the anniversary of the filing date Correct answer.
Exactly on 3 March 2025 without any grace period
Within 30 days of the grant decision
Only after the patent is granted

Explanation

Renewal fees in Switzerland fall due on the last day of the month preceding the anniversary of the filing date, and a late payment period with a surcharge is available. The obligation is tied to the filing anniversary, not to the grant date.

Question 29Patent law (national and international)

Which condition must be satisfied for an invention to be regarded as new under Swiss law?

It must be commercially exploitable
It must have been kept secret until filing
It must be disclosed in a granted Swiss patent
It must not form part of the state of the art Correct answer.

Explanation

Novelty requires that the invention does not form part of the state of the art, which comprises everything publicly available before the relevant date. Commercial exploitability and prior secrecy are not tests for novelty.

Question 30Patent law (national and international)

An applicant discloses an invention at a recognised Swiss trade fair and files the Swiss application six months later. Which rule is most relevant to preserving novelty?

The research exemption
The priority right under the Paris Convention
The exhibition grace period provided by the Patents Act Correct answer.
The twelve-month grace period of the EPC

Explanation

The Swiss Patents Act provides a limited grace period for disclosures at officially recognised exhibitions, so the earlier display does not destroy novelty. The Paris priority right presupposes an earlier filing, and the research exemption concerns infringement, not novelty.

Question 31Patent law (national and international)

Which requirement concerns whether the claimed invention can be made or used in any kind of industry?

Inventive step
Industrial application Correct answer.
Sufficiency of disclosure
Unity of invention

Explanation

Industrial application asks whether the subject-matter can be made or used in any kind of industry, including agriculture. Inventive step concerns non-obviousness, sufficiency concerns enablement, and unity concerns the number of independent inventions claimed.

Question 32Patent law (national and international)

A Swiss patent is granted for a product. A competitor makes the product in Switzerland for export to a non-member state. Which statement best reflects the territorial reach of the Swiss patent?

The patent has no effect because the destination is abroad
Only acts of sale inside Switzerland can ever infringe
Making the product in Switzerland can infringe regardless of where the product is later sold Correct answer.
Exporting is always privileged because the product leaves Switzerland

Explanation

The Swiss patent has territorial effect on acts performed in Switzerland, and manufacturing the patented product in Switzerland is an infringing act irrespective of the destination of the goods. The place of subsequent sale does not neutralise the domestic manufacturing act.

Question 33Patent law (national and international)

Which act by a third party is expressly permitted as a research exemption under the Swiss Patents Act?

Import of the patented product for resale
Commercial manufacture of the patented product for stockpiling
Acts done for experimental purposes relating to the subject-matter of the invention Correct answer.
Sale of the patented product without the patentee's consent

Explanation

Experimental acts relating to the subject-matter of the patented invention are exempt, allowing research on the invention. Commercial manufacture, sale and import without consent fall within the patentee's exclusive rights.

Question 34Patent law (national and international)

An applicant files a European patent application and wishes to obtain a Swiss national patent instead. Which route is generally available after the European application has been refused?

Filing a fresh application that keeps the original filing date without any formal basis
Requesting the Federal Patent Court to grant the patent
Automatic grant of a Swiss patent without examination
Conversion into a national Swiss application under the applicable provisions Correct answer.

Explanation

The EPC provides for conversion of a European application into a national application where the European procedure fails, subject to national requirements. There is no automatic grant, and the Federal Patent Court does not grant patents.

Question 35Patent law (national and international)

What is the legal effect of a priority claim based on an earlier national application?

It replaces the earlier application automatically
It extends the term of the later patent by twelve months
It guarantees grant without substantive examination
The later application is treated as filed on the priority date for novelty and inventive step assessment Correct answer.

Explanation

Priority gives the later application the benefit of the earlier filing date when assessing prior art, so disclosures between the two dates do not count against it. It does not extend the patent term or guarantee grant.

Question 36Patent law (national and international)

An applicant files a PCT application and wants to enter the Swiss national phase. Which statement best describes the applicable time limit?

Entry must occur within 12 months from the international filing date
Entry must occur before publication of the international application
Entry must occur within 30 months from the priority date unless a longer period is provided Correct answer.
Entry must occur within 5 years from the priority date

Explanation

Switzerland applies the 30-month time limit from the priority date for national phase entry, in line with PCT practice. The 12-month period is the priority period, and publication does not close the national phase.

Question 37Patent law (national and international)

Under the EPC, which body is responsible for deciding opposition proceedings against a granted European patent?

The Opposition Division of the European Patent Office Correct answer.
The Swiss Federal Patent Court
The Boards of Appeal directly
The national patent offices of the member states

Explanation

Oppositions are examined by the EPO's Opposition Division, with appeal lying to the Boards of Appeal. National courts handle national validity and infringement disputes, and national offices do not decide EPO oppositions.

Question 38Patent law (national and international)

A European patent designating Switzerland is revoked in EPO opposition proceedings. What is the consequence for Switzerland?

The patent is converted into a Swiss national patent automatically
The patent remains in force in Switzerland until a national court revokes it
Only the claims are amended while the patent stays in force
The European patent is deemed never to have existed in Switzerland Correct answer.

Explanation

Revocation of a European patent has effect in all designated states, so the patent is treated as never having existed in Switzerland. No separate national revocation is needed, and automatic conversion does not occur.

Question 39Patent law (national and international)

An employee in Switzerland creates an invention in the course of employment. Which statement best reflects the default allocation of rights?

The employer may acquire the rights under the employment relationship and the Patents Act Correct answer.
The rights pass to the Swiss Confederation
The rights vest jointly in the employer and the Federal Institute of Intellectual Property
The employee always retains all rights regardless of the employment contract

Explanation

Under the Swiss Patents Act and employment law, inventions made in the performance of employment duties may be claimed by the employer, subject to notification and compensation rules. The employee does not automatically keep all rights, and no public body acquires them.

Question 40Patent law (national and international)

What is the essential condition for a prior-user right to protect a party accused of infringement in Switzerland?

The party filed a secret application before the patentee
The party began using the invention in good faith before the priority date and continued that use Correct answer.
The party obtained a licence after the patent was granted
The party published the invention before the priority date

Explanation

A prior-user right protects a person who, in good faith, began using the invention in Switzerland before the priority date and continued that use. A later licence or a pre-priority publication does not create such a right.

Question 41Patent law (national and international)

An examiner objects that the claims are broader than the disclosure. Which legal issue is primarily raised?

Whether the invention is industrially applicable
Whether the disclosure sufficiently enables the skilled person to carry out the claimed subject-matter Correct answer.
Whether the applicant paid the renewal fees
Whether the claims are in the correct language

Explanation

Claims broader than the disclosure raise sufficiency: the skilled person must be able to carry out the full scope claimed without undue burden. Fee payment, industrial application and language are separate requirements.

Question 42Patent law (national and international)

A Swiss patent claims a narrow selection of compounds from a broad prior-art genus. Which test best supports inventive step for the selection?

The selection must produce an unexpected technical effect across the claimed range Correct answer.
The selected compounds must be chemically simpler than the genus
The selection must have been disclosed in a later publication
The selection must include every compound of the genus

Explanation

A selection from a broad genus can be inventive where it delivers an unexpected technical effect over the whole claimed range. Chemical simplicity, completeness of the selection, or later disclosure do not establish inventive step.

Question 43Patent law (national and international)

Which of the following subject-matters is expressly excluded from patentability under the Swiss Patents Act?

Methods for the treatment of the human body by surgery or therapy Correct answer.
Industrial chemical processes
Genetic engineering products
Pharmaceutical compositions

Explanation

Methods of surgical or therapeutic treatment of the human or animal body are excluded from patentability, although the products used in such methods may be claimed. Chemical processes, pharmaceutical compositions and genetic engineering products are patentable subject-matter.

Question 44Patent law (national and international)

An applicant wants to protect a plant variety in Switzerland. Which form of protection is specifically designed for that subject-matter?

A Swiss patent for the variety as such
A design registration
A trademark registration
A plant variety right under the plant variety protection regime Correct answer.

Explanation

Plant varieties are protected through the specialised plant variety protection regime rather than patents for the variety as such. Trademarks and designs protect different subject-matter and cannot cover a plant variety.

Question 45Patent law (national and international)

A third party requests that a granted Swiss patent be declared null. Which ground is recognised by the Patents Act?

The patentee did not exploit the patent in Switzerland
The patentee charged excessive licence fees
The invention was not patentable because it lacked novelty Correct answer.
The patentee failed to advertise the patent

Explanation

Nullity can be based on substantive grounds such as lack of novelty, inventive step, sufficiency or excluded subject-matter. Licence pricing, local exploitation and advertising are not nullity grounds under the Patents Act.

Question 46Patent law (national and international)

Which statement best describes the relationship between a Swiss national patent and a European patent designating Switzerland?

The European patent automatically replaces any national patent for the same invention
A national patent cannot coexist with a European patent for the same invention
They are independent rights, and the European patent has the same effect in Switzerland as a national patent Correct answer.
The European patent has no effect in Switzerland until confirmed by the Federal Patent Court

Explanation

A European patent designating Switzerland has the same effect as a national patent, but the two rights remain independent and can coexist. There is no automatic replacement or need for judicial confirmation of effect.

Question 47Patent law (national and international)

What is the function of the designation of the inventor in a Swiss patent application?

To prove that the invention is novel
To determine the scope of the claims
To identify the inventor as required by law, without affecting the scope of protection Correct answer.
To establish the priority date

Explanation

The designation of the inventor fulfils a statutory naming requirement and protects the inventor's moral rights. It does not define claim scope, establish priority or prove novelty.

Question 48Patent law (national and international)

A patentee discovers that a competitor is selling an infringing product in Switzerland. Which provisional measure can the patentee seek from the competent court?

An interim injunction prohibiting the continued sale, subject to the statutory conditions Correct answer.
Automatic criminal conviction of the competitor
Revocation of the competitor's business licence
Seizure of the competitor's entire assets without a court order

Explanation

Provisional measures such as an interim injunction can be requested to stop ongoing infringement pending the merits, subject to conditions such as prima facie infringement and urgency. Courts do not impose criminal convictions or licence revocations through civil interim relief.

Question 49Patent law (national and international)

Which statement correctly describes the requirement of unity of invention in a Swiss application?

The application must relate to a single inventive concept or a group of inventions linked by that concept Correct answer.
The application may claim unrelated inventions without restriction
Every claim must be in a separate application
Unity applies only to European patents

Explanation

Unity requires that the claims share a single general inventive concept, allowing a group of linked inventions in one application. Unrelated inventions must be divided, and the requirement applies to national applications as well.

Question 50Patent law (national and international)

An applicant realises after filing that the description omits an essential feature needed to carry out the invention. Which statement best reflects the permissible correction?

The applicant must file a new application without any date effect
Amendments may not add subject-matter beyond the content of the application as filed Correct answer.
The omission automatically invalidates the application
The applicant may freely add the missing feature at any time

Explanation

Amendments are limited by the prohibition on adding subject-matter beyond the original disclosure, so a missing essential feature generally cannot be added later. The application is not automatically invalid, and a new filing would lose the original date.