International (PCT)

There is no such thing as an international patent, and a PCT international patent application does not create one. It is a single filing under the Patent Cooperation Treaty that reserves your priority date in all 158 contracting states at once, produces a search report and a written opinion on patentability, and then hands the actual grant decision back to each national office. What you are really buying is time: roughly 18 extra months before you have to commit money country by country.

Everything about the system follows from one fact. Patents are territorial. A U.S. patent stops infringement in the United States and nowhere else. A German patent stops nothing in Japan. If you want rights in twelve countries, you need twelve grants, from twelve offices, under twelve bodies of law. The PCT does not change that arithmetic. It changes when you have to pay for it.

Why territoriality drives the whole system

A patent is a grant from a sovereign, so its reach ends where that sovereign’s authority ends. There is no global registry that issues a worldwide right, and the Paris Convention and the PCT, the two treaties that matter most here, are coordination instruments rather than grant instruments. They harmonize dates and procedures. They do not create a supranational patent.

The practical consequence surprises people constantly: the same application, with identical claims, can be granted in Europe and rejected in the United States, or narrowed sharply in China and allowed broadly in Japan. Each office applies its own prior art standards, its own eligibility rules, and its own claim drafting conventions. A PCT written opinion that says your invention looks novel and inventive binds nobody.

What the PCT actually is: a procedural clock

Strip away the acronyms and the PCT is a schedule. Dates run from your priority date, meaning your earliest filing, commonly a U.S. provisional.

• Month 0. Priority filing. In the United States this is often a provisional application, which starts the clock without being examined.
• Month 12. The Paris Convention deadline. This is when you must file the PCT application to keep your original date abroad. Miss it and your own publication or sale generally becomes prior art against you everywhere.
• Month 16 or so. The International Searching Authority issues an International Search Report and a Written Opinion. The search report lists prior art. The written opinion is a preliminary, non-binding view of novelty, inventive step, and industrial applicability. Treat it as intelligence, not a verdict.
• Month 18. The application publishes. Publication is measured from the priority date, so it happens whether or not anything is granted, and whether or not you like what the search report said.
• Month 22, optionally. You may file a Demand under Chapter II for international preliminary examination, which produces an IPER. The deadline is the later of 22 months from priority or three months from the written opinion. It is a chance to amend and argue before the national phase, and in most modern practice it is skipped, because the written opinion already told you most of what you needed to know.
• Months 30 to 31. The national phase. You choose which countries you actually want, pay their fees, file their translations, and hire their agents. The United States uses 30 months. The European Patent Office uses 31.

The elegance is in what happens at month 30 rather than month 12. Without the PCT, the Paris route forces you to pick your countries and pay all of them at twelve months, when you usually know nothing about market traction and little about your prior art.

Cost deferral is the real product

The PCT is frequently sold as a way to save money. It is not. Adding the international phase adds fees. What it does is move the largest expense, the national phase, about a year and a half into the future, and it gives you a search report before you spend it.

That deferral has real option value. At month 12 you may have a prototype and a hypothesis. At month 30 you may have revenue, a distribution deal, a competitor, or a failed pilot. Deciding which of Europe, China, Japan, Korea, and Brazil is worth $5,000 to $15,000 each is a very different exercise with 18 more months of evidence in hand. Many applicants use the search report to walk away entirely, which is itself a good outcome: an early, cheap no.

The alternatives: Paris route, regional grants, and the Unitary Patent

The PCT is not the only path abroad.

The Paris route means filing directly in each target country within twelve months of your priority date, skipping the PCT entirely. It is faster to grant and cheaper if you know for certain that you want two or three specific countries and nothing else. It is the right call more often than the PCT’s popularity suggests.

Regional systems sit between the PCT and national filings. The European Patent Office examines centrally and issues a European patent, but that grant is not a single right. It must then be validated in each member state you want, which historically meant translations and separate national renewal fees, and enforcement happened in national courts. Since June 1, 2023, a granted European patent can instead be registered as a Unitary Patent, a single right covering the participating EU member states with one renewal fee, litigated in the new Unified Patent Court. The trade-off is concentration of risk: one UPC revocation can kill the patent across all participating states at once, where the old bundle had to be attacked country by country.

Two traps that catch American filers

Absolute novelty abroad. The United States gives an inventor a one-year grace period under 35 U.S.C. § 102(b)(1) for the inventor’s own disclosures. Most of the world does not. Under the European Patent Convention and in China, Japan, and elsewhere, a public disclosure before your priority filing is absolute novelty destroying prior art, including your own conference talk, Kickstarter page, or trade show demo. The § 102(b)(1) grace period is a purely domestic rescue. It saves your U.S. rights and does nothing for the other 157 PCT states. File before you disclose, not after.

The foreign filing license. Under 35 U.S.C. § 184, an invention made in the United States generally may not be filed abroad without a license from the USPTO. In ordinary practice this is nearly invisible: filing a U.S. application first triggers an automatic license, usually granted on the filing receipt, and after six months the license is implied absent a secrecy order. But filing directly in a foreign office first, without a license, can forfeit the U.S. patent under 35 U.S.C. § 185. Other countries, including the United Kingdom, India, and China, have their own versions of this rule, which matters for distributed engineering teams where “where was the invention made” is a genuine question.

Frequently asked questions

What is a PCT international patent application? A PCT application is a single filing under the Patent Cooperation Treaty that reserves your filing date in all 158 contracting states at once. It is a procedural placeholder, not a patent. No examiner grants anything on a PCT application. It produces a search report and a non-binding written opinion, then you enter the national phase at 30 or 31 months from your priority date and each country examines separately.

Does a PCT application give you an international patent? No. There is no such thing as an international patent. Patents are territorial: each country grants rights enforceable only inside its own borders. The PCT centralizes the front end of the process, the filing and the search, but every grant decision is still made country by country, and offices routinely reach different outcomes on the same application.

What is the deadline to file a PCT application? Twelve months from your earliest priority filing, under the Paris Convention. That deadline is unforgiving. Miss it and you generally lose the ability to claim your original date abroad, which usually means your own published application becomes prior art against you. The PCT then extends the decision point on individual countries out to 30 months.

How much does a PCT application cost? The international phase typically runs a few thousand dollars in official fees, including the international filing fee, transmittal fee, and search fee, plus attorney time. The expensive part is the national phase, where each country adds its own fees, local agents, and translations. The PCT does not reduce that total. It defers it by roughly 18 months.

Authorities and sources

• WIPO: PCT, the International Patent System
• WIPO: PCT Contracting States
• Patent Cooperation Treaty, full text (WIPO)
• Paris Convention for the Protection of Industrial Property (WIPO Lex)
• 35 U.S.C. § 102: Conditions for patentability, novelty (Cornell LII)
• 35 U.S.C. § 184: Filing of application in foreign country (Cornell LII)
• 35 U.S.C. § 185: Patent barred for filing without license (Cornell LII)
• 35 U.S.C. § 371: National stage, commencement (Cornell LII)
• USPTO: Applying for patents internationally (PCT)
• MPEP Chapter 1800: Patent Cooperation Treaty
• European Patent Office: Unitary Patent
• Agreement on a Unified Patent Court (EUR-Lex, OJ C 175, 20.6.2013)

Going further: PCT and international patents, how filing actually works .

This page is general legal information, not legal advice, and it does not create an attorney-client relationship.