Patent prosecution is the process of getting a patent granted. Drafting the application, filing it, and negotiating with an examiner until the claims are allowed or the application is abandoned.
The word causes trouble. It means examination before the Patent Office and has nothing to do with criminal prosecution. In writing for a general audience, "patent prosecution" rather than "prosecution" saves a moment of confusion every time.
Prosecution versus litigation
These are different activities, usually done by different people, and conflating them is the most common misunderstanding in the field.
| Patent prosecution | Patent litigation | |
|---|---|---|
| Objective | Obtain a patent | Enforce or invalidate one |
| Forum | USPTO | Federal district court, ITC, PTAB |
| Parties | Applicant and examiner | Patentee and accused infringer |
| Nature | Ex parte, negotiated | Adversarial |
| Qualification | Registered patent attorney or agent | Any admitted litigator |
| Technical degree | Required | Not required |
| Typical duration | 2-3 years | 2-3 years |
Registration is the hard line. To prosecute applications before the USPTO you must pass the patent bar, which requires a technical or scientific degree. A general commercial lawyer, however senior, cannot file an office action response.
A patent litigator needs no technical qualification at all. They argue infringement and validity in court under normal rules of practice, and many excellent patent litigators are not registered before the Office.
Some practitioners do both. Most specialise, and the skills genuinely differ — prosecution is careful drafting and negotiation over years, litigation is argument under adversarial pressure.
Patent attorney or patent agent
Both are registered. The difference is everything outside USPTO practice.
| Patent agent | Patent attorney | |
|---|---|---|
| Prosecute applications | Yes | Yes |
| Registered before the USPTO | Yes | Yes |
| Admitted to a state bar | No | Yes |
| Give general legal advice | No | Yes |
| Draft assignments and licences | No | Yes |
| Litigate | No | Yes |
| Typical cost | Lower | Higher |
For prosecution alone, an agent is often the better economics. For anything involving contracts, ownership disputes, or advice about enforcement, an attorney is required.
The stages
Provisional application, optional
Twelve months of priority without starting the twenty-year term clock. A provisional is never examined and never becomes a patent. It establishes a priority date, and a non-provisional must be filed within twelve months to claim it.
The main use is timing. Filing a provisional before a conference, a demonstration or a funding pitch preserves rights that a public disclosure would otherwise destroy — immediately in most countries, and after twelve months in the US.
It must still enable the invention. A provisional that does not support the claims later filed provides no priority for them.
Non-provisional filing
The application that gets examined. Specification, drawings, claims, oath or declaration, and fees.
This starts the twenty-year term clock, which is why enforceable life is always shorter than twenty years — see how long does a patent last.
Publication at eighteen months
Applications publish eighteen months from the earliest priority date unless non-publication was requested at filing, which is only available where no foreign filing is intended.
Publication makes the application prior art against later applications, and visible to competitors. It also starts provisional rights running — a patentee can recover a reasonable royalty for infringement occurring between publication and grant, if the claims are substantially identical.
First office action
Averaging 19.9 months in FY2024. The examiner searches the prior art and issues a written rejection, objection, or occasionally an allowance.
Most applications are rejected first time. It is the normal course of prosecution — see office action for the rejection types and how to respond.
Response, and repeat
Three months to respond, extendable to six for a fee that also costs Patent Term Adjustment day for day.
A second action commonly follows, frequently marked final. After a final action the options are an after-final response, an appeal to the PTAB, a Request for Continued Examination, or abandonment.
Allowance and issue
A notice of allowance means the claims are allowed. The issue fee is due within three months and is not extendable.
The patent grants and the maintenance fee clock starts — 3.5, 7.5 and 11.5 years from that date.
The timeline in practice
| Stage | Typical timing |
|---|---|
| Provisional to non-provisional | Up to 12 months |
| Filing to publication | 18 months from priority |
| Filing to first office action | ~19.9 months (FY2024 average) |
| First response to second action | 3-6 months |
| Filing to grant, no RCE | ~26.3 months (FY2024 average) |
| Filing to grant, with RCE | ~30 months |
Variation by technology is substantial. Software and business method applications routinely run longer, largely because section 101 subject-matter rejections require multiple rounds and are difficult to overcome by argument. Mechanical applications tend to move faster.
Two patents filed the same day in different fields can have materially different enforceable lives as a result, because every month of pendency is a month of term consumed.
Accelerating prosecution
| Route | What it does | Cost |
|---|---|---|
| Track One | Targets final disposition in 12 months | Additional USPTO fee |
| Patent Prosecution Highway | Accelerates where allowed abroad | No additional official fee |
| Accelerated examination | Faster, with a pre-examination search | Applicant does more work |
| Age or health petition | Available to inventors over 65 or in poor health | Petition only |
Track One is the straightforward option. It costs an additional fee and compresses pendency substantially, which preserves two or three years of enforceable term.
The trade is usually worth making on a commercially important application and usually not on a speculative one. A patent that will drive a product line is worth accelerating; one filed to see what happens is not.
The Patent Prosecution Highway is underused. Where a corresponding application has been allowed in a participating office abroad, PPH accelerates the US examination at no additional official fee. Applicants with foreign filings frequently do not realise it is available.
A worked example: the cost of extensions
An application filed March 2015, three office actions before allowance, granted June 2019.
With prompt responses
| Event | Timing | Applicant delay |
|---|---|---|
| First action | Month 20 | — |
| Response | Month 23 (within 3 months) | 0 days |
| Second action | Month 30 | — |
| Response | Month 33 | 0 days |
| Final action | Month 40 | — |
| Response | Month 43 | 0 days |
| Allowance | Month 48 | — |
Patent Term Adjustment preserved in full. Whatever Office delay accrued is credited without reduction.
With routine extensions
| Event | Timing | Applicant delay |
|---|---|---|
| First action | Month 20 | — |
| Response | Month 26 (full extension) | ~90 days |
| Second action | Month 33 | — |
| Response | Month 39 (full extension) | ~90 days |
| Final action | Month 46 | — |
| Response | Month 52 (full extension) | ~90 days |
| Allowance | Month 57 | — |
Roughly 270 days of applicant delay charged, reducing Patent Term Adjustment by the same amount, plus nine months of additional pendency consuming term directly.
The cost is close to eighteen months of enforceable life — at the end of the patent's term, when the technology is established and the patent is worth most. The extension fees themselves are a small fraction of that value.
The trade is sometimes right. An extension that produces a better response is better than a rushed one that draws another rejection. The point is that it should be a decision each time rather than a default.
Continuations and the family
A continuation is a further application claiming priority to a pending parent, with the same disclosure and different claims. It lets an applicant pursue additional scope while the parent proceeds to grant.
| Type | Disclosure | Claims | Common purpose |
|---|---|---|---|
| Continuation | Same as parent | Different | Pursue broader or different scope |
| Divisional | Same as parent | To a restricted-out invention | Respond to a restriction requirement |
| Continuation-in-part | Parent plus new matter | May cover new matter | Add developments made since filing |
The term does not reset. All members run twenty years from the earliest non-provisional filing, so a continuation filed in year four has sixteen years of term rather than twenty.
Terminal disclaimers frequently apply. Where a continuation is rejected for obviousness-type double patenting over its parent, a terminal disclaimer caps its term at the parent's expiry — potentially eliminating Patent Term Adjustment the continuation had earned.
A pending continuation is strategically valuable. It allows claims to be drafted later, with knowledge of what competitors have built, which is worth more than most applicants realise while the family is still open.
How prosecution constrains enforcement
Everything in the file history is public and permanent, and it is the first thing read by anyone assessing the patent — a potential infringer, a buyer, a PTAB petitioner.
Narrowing amendments create prosecution history estoppel, limiting what the doctrine of equivalents can later reach. Scope surrendered to overcome prior art generally cannot be recaptured.
Arguments surrender scope without amendments. Distinguishing a reference by arguing your invention does not do X tells the world that X is outside the claim.
Extensions cost term. As above, day for day.
The discipline is the same throughout. Amend as narrowly as the rejection requires. Argue no more broadly than necessary. Respond within three months unless there is a reason not to. Each of these costs something small during prosecution and preserves something significant later.
Before you start prosecution
- File before any public disclosure, because most countries have no grace period.
- Decide on a provisional based on timing needs, not cost — it buys twelve months without consuming term.
- Choose an attorney or agent with the right technical background, because claim drafting requires understanding the invention.
- Consider Track One on anything commercially important.
- Check whether the Patent Prosecution Highway is available if you have allowed foreign counterparts.
- Respond within three months by default.
- Keep a continuation pending on anything strategically significant.
- Read every response before it is filed, because you will be reading it again in litigation.