Federal Patent CourtObservations & Oppositions builder

Nullity action

Section 81 PatGNichtigkeitsklage

An action at the Federal Patent Court to declare a German patent, or the German part of a European patent, void against everyone. It opens once no opposition is possible or pending. The court fee follows the value in dispute.

Start an invalidity search How IPtorch builds it
BPatG Federal Patent Court 1. Statement of claim 2. Claim chart 3. Exhibit D1 4. Exhibit D2 5. D1 translation Klage Chart D1 D2 D1 (DE) Unsigned draft
Pleading, chart and exhibits in one unsigned bundle.

At a glance

After the opposition route closes

4.5 times the GKG fee on the value in dispute (checked 22 Sep 2026)

Who can file
Anyone. Usurpation only by the injured party; lack of entitlement only by the person entitled under Art. 60(1) EPC.
Deadline
None while in force, but not before the Section 81(2) bar falls away. After expiry, a continuing legal interest is needed.
Official fee
Fee 402 100: 4.5 times the Section 34 GKG single fee on the value in dispute, minimum EUR 121. Service waits for payment.
Anonymous
No. The claimant is named in the complaint.
Representation
Not compulsory (Section 97(1) PatG), but a party without a German domicile, seat or establishment needs a representative.
Language
German (Section 126 PatG), with translations of the passages relied on annexed.
How it is filed
In writing at the Federal Patent Court. Attorneys-at-law and public bodies must file electronically, for example by beA. Never email.
Party status
Claimant in court proceedings: oral hearing as a rule, a costs order, and appeal to the Federal Court of Justice.

What it is

Nullity action, in brief

A nullity action is a court pleading with a named claimant and defendant, a value in dispute, a costs order and a court fee that must be paid before the complaint is served. It is not an enlarged opposition, and it does not decide infringement.

It is barred while an opposition is possible or pending (Section 81(2) PatG) and is brought against the registered proprietor. A German patent is attacked under Section 22 PatG, the German part of a European patent under Art. II Section 6 IntPatÜbkG. Nullity is retroactive and binds everyone; dismissal binds only the parties.

Grounds it can carry

  • Lack of noveltySection 22(1) with Sections 21(1) no. 1 and 3 PatG
  • Lack of inventive stepSection 22(1) with Sections 21(1) no. 1 and 4 PatG
  • Excluded subject matter or no industrial applicationSection 22(1) with Section 21(1) no. 1 PatG
  • Insufficient disclosureSection 22(1) with Section 21(1) no. 2 PatG
  • Added matter, or extended scope of protectionSection 22(1) PatG, with Section 21(1) no. 4
  • Usurpation or lack of entitlement, restricted standingSection 21(1) no. 3 PatG; Art. II Section 6(1) no. 5 IntPatÜbkG

Use it when

  • The patent is granted, the opposition period has expired with no opposition pending, and it should fall against everyone.
  • You have been sued for infringement and want the patent itself destroyed, in separate proceedings.

Choose another route when

  • The nine-month opposition period at the DPMA or EPO is still running, or an opposition is pending. Opposition
  • You have been sued while somebody else's German opposition is still pending. Intervention
  • The target is a European patent with unitary effect. Revocation action

How IPtorch builds it

From search to filing, minus the signature.

The invalidity search runs on into this filing when it ends, with no second click. Three model families take turns, so a draft is never checked by the model that wrote it.

  1. 1SearchClaims split into limitations, thousands of candidates screened, at least 50 references read in full.Gemini models read and check
  2. 2Claim mapA verbatim quotation and its location behind every limitation.Every cell checkable
  3. 3DraftWrites the papers in the office's format and language.Claude Opus 5.5 (Anthropic)
  4. 4ReviewChecks each citation against its document and builds the forms.Sol 6 (OpenAI)
  5. 5AdjudicateHigh strength: a third family rules on every objection.Gemini 3.1 Pro (Google)
  6. 6FolderUnsigned PDFs, ready for a professional to review, sign and file.Nothing is filed

What the builder does for this filing

  • It starts from an invalidity search with at least 50 references read in full and re-qualifies each under the branch's own rule: Section 3 PatG for a German patent, Art. 54 EPC for a European one.
  • It writes a feature analysis of every attacked independent claim, then attacks claim by claim and ground by ground, dependent claims individually, with prior art numbered NK1, NK2.
  • Before drafting it checks the Section 81(2) bar, the registered proprietor as defendant and, for a European patent, no unitary effect; counsel approves the plan and the value in dispute at a plan gate.
  • It refuses before any spend if the claimant's name and address are missing, and nothing is filed or paid.

In the folder

  • Statement of claimRequests first, value in dispute, feature analysis, claim-by-claim attack
  • Exhibit index, K and NK seriesPrior art numbered NK1, NK2; other exhibits K1, K2
  • Copies of every cited documentWith labelled machine translations printed beside the original text
  • Value in dispute and court fee calculationInternal: 4.5 times the Section 34 GKG single fee
  • Form A 9532 dataFee number 402 100, sent with the complaint
  • Copies for the defendantPaper copies and data carriers under Section 81(4) PatG
  • Power of attorney for the proceedingsUnder Section 97(5) PatG, signed by the claimant's officer

Builder strength

You choose how hard it is checked.

You pay for the tokens the sessions use, at the models' list prices plus a 30% fee, not for the time allowed. How pricing works

Low

40 minutesabout 10 million tokens (roughly $10 to $30)

  1. Opus 5.5 drafts the submission
  2. Sol 6 builds and checks the final forms

Medium

2 hoursabout 20 million tokens (roughly $20 to $60)

  1. Opus 5.5 drafts the submission
  2. Sol 6 reviews and rebuilds the content
  3. Opus 5.5 builds the filing folder
  4. Sol 6 checks the form

High

5 to 6 hoursabout 60 million tokens (roughly $50 to $200)

  1. Opus 5.5 drafts the submission
  2. Sol 6 runs a deep prior-art search
  3. Opus 5.5 rebuilds the submission against the evidence
  4. Sol 6 attacks it as an adversarial examiner
  5. Gemini 3.1 Pro adjudicates the objections
  6. Opus 5.5 applies the fixes and builds the filing folder
  7. Scripted checks of the filing folder
  8. Sol 6 audits the whole folder
  9. Convergence gate

If the gate fails, one repair round: opus 5.5 repairs what the gate found, sol 6 audits the repair, convergence gate, again.

What stays with you

You review, sign and file.

  • An attorney-at-law files through beA; a patent attorney through eBO or on signed paper.
  • Sign SEPA mandate A 9530 by hand and post the original to the DPMA weeks ahead.
  • Have the claimant's officer sign the power of attorney for the proceedings.
  • Keep the account funded so the court fee is debited and the complaint served.

Where these go wrong

What the builder guards against.

  • Filing too early. While an opposition is possible or pending, Section 81(2) PatG bars the action.
  • Suing the wrong defendant because the register changed. Check the registered proprietor on the filing day.

More filings in Germany

DPMA and the Federal Patent Court

All 17 filings

Start with the evidence.

Upload the patent or enter its number. The invalidity search charts every claim, and the builder takes it from there.

Start an invalidity search

Facts checked against the office's rules on 22 September 2026. IPtorch is not a law firm and this page is not legal advice. The builder's output is unsigned work product for a registered professional to review, sign and file; nothing is filed and no fee is paid for you. Confirm current requirements, fees and deadlines with the receiving office.