Key Takeaways

  • Patent interference is a proceeding used to determine which party was the first to invent when two or more claim the same subject matter.
  • These proceedings apply only to patents or applications with filing dates before March 16, 2013, under the old “first-to-invent” system.
  • Interferences are initiated either by a patent examiner’s suggestion or by a party’s request to the USPTO.
  • The process involves a preliminary phase (validity challenges) and a priority phase (deciding who invented first).
  • Evidence such as invention records, lab notebooks, and reduction-to-practice documents are critical in proving priority.
  • Few disputes proceed to interference—only about 1% of cases escalate to this stage.
  • Interferences differ from litigation: they are handled by the Patent Trial and Appeal Board (PTAB), apply the “broadest reasonable interpretation” standard, and involve limited discovery

Patent interference involves the competition between at least two agents over the rightful ownership of a patent. These issues are contested through the U.S. Patent and Trademark Office (USPTO) and are then presented to the Patent Trial and Appeal Board for review. The job of this board is to conclude rightful ownership, which is awarded to the party that either:

  • Thought of the concept and acted on it before the other party
  • Thought of the concept first and put forth acceptable effort to act on it before the other party began their own initiation

What Are Patent Interferences?

Patent interferences occur when a patent is requested by an agency, only to find out that there are other agencies that are also requesting a patent for the same concept (or already own the rights). As a patent cannot be owned by more than one entity, a clear owner must be established. Determining who is the true owner of the patent is called determining priority.

Instances of patent interference only occur when there are two or more agencies that are claiming the rights to the same concept; general similarities do not apply and would therefore not be considered.

It is important to note that while an agency can claim true ownership over a previously-issued patent, the patent in question must have been granted less than one year prior, and the agency competing against the original owner must legally qualify to own a patent.

While conflicts over true ownership do occur, only 1 percent of disputes continue with patent interference proceedings. When cases do move forward, each party is responsible for providing support for their own claim. This evidence is then reviewed by a panel of three judges. In addition to submissions of evidence, the review process focuses on the conception of the invention, which is the idea itself, and reduction to practice, which is the action of bringing the idea to life.

Proving reduction to practice is essential in patient interference; however, the submission of an in-depth patent application similarly allows the applicant to meet this criteria.

There are some instances of dispute that result in the concept being deemed not patentable, in which case neither party is able to claim ownership following the proceedings.

Finally, if after the proceedings an agent is unhappy with the conclusion of an investigation, they can request re-investigation through the United States Court of Appeals for the Federal Circuit.

Historical Context and Current Relevance

Patent interference proceedings are a product of the pre-America Invents Act (AIA) patent system, which awarded rights to the first person to invent rather than the first to file. As a result, interferences only apply to applications or patents with an effective filing date before March 16, 2013. Modern disputes are generally addressed through derivation proceedings, which determine whether one inventor improperly derived an invention from another.Despite their limited scope today, interferences remain relevant in some long-pending cases and can still have significant impact on ownership of valuable intellectual property.

How Is Patent Interference Initiated?

There are two ways to initiate patent interference:

  • Through the suggestion of a patent examiner by sending the application to the USPTO Board of Patent Appeals.
  • Through the request of the applicant by sending their request to the patent examiner.

In cases where patent interference is initiated through the applicant's request, they must:

  • Identify the claim being submitted.
  • Identify the opposing party.
  • Identify their reasoning for requesting patent interference.

Ultimately, the USPTO Patent Board makes the final decision regarding moving forward with patent interference. If they decided in favor of patent interference, each party is informed via mail, outlining their role in the upcoming proceedings.

In each proceeding, there will be a senior party, who is assumed to be the rightful owner, and one or more junior parties. The senior party is decided based upon the dates each application was originally submitted; the owner of the first application submitted is considered the rightful owner of the patent until declared otherwise.

Stages of a Patent Interference Proceeding

Patent interferences unfold in two key stages:

  1. Preliminary Phase – Each party can challenge the validity or patentability of the opponent’s claims. This may include arguments based on prior art, written description, or derivation. Limited discovery, such as expert depositions, may also occur. If one party’s claims are ruled unpatentable, the other is awarded priority.
  2. Priority Phase – If both parties maintain at least one valid claim, the PTAB then determines who was the first to invent. Evidence often includes invention records, laboratory notebooks, communications, and testimony. This phase also allows limited discovery, including exchange of confidential documents.

How Do You Win a Patent Interference?

Even if you were not the first party to attempt to bring the concept to life, you can still win a patent interference if you can prove that you were the first to think of the idea. However, this is only possible if the party can prove that they attempted to act on the idea before their competitor began initialization. Similarly, the party must be able to provide a legitimate reason explaining why they were not first. Acceptable explanations may include delays in obtaining the following:

  • Supplies
  • Staff
  • Official clearance

Types of Evidence Considered

Winning a patent interference relies on the ability to prove conception and reduction to practice. Common forms of evidence include:

  • Invention notebooks with signed and dated entries.
  • Prototype testing data showing successful implementation.
  • Correspondence documenting early conception or collaboration.
  • Expert testimony that supports reduction-to-practice efforts.
    The PTAB weighs this evidence under the “preponderance of evidence” standard, meaning a claim must be more likely than not to be true. Strong, contemporaneous records can tip the balance in close cases

How Do Interferences Differ From Traditional Litigation?

Interferences differ from traditional litigation in the following ways:

  • Applications are processed using the broadest reasonable interpretation.
  • Proof is established through the preponderance of evidence.
  • Applications are evaluated by technically-trained judges.

Advantages and Limitations of Patent Interference

Patent interference offers distinct advantages compared to litigation in federal courts:

  • Specialized Judges: PTAB judges have technical training, providing deeper subject-matter understanding.
  • Efficiency: Proceedings often resolve more quickly than district court litigation.
  • Focused Issues: The PTAB limits disputes to priority and patentability, avoiding broader commercial questions.

However, limitations include:

  • Restricted Availability: Only applies to pre-2013 filings.
  • Limited Discovery: Parties cannot use the broad discovery tools available in federal litigation.
  • High Stakes: An adverse ruling can eliminate an entire patent family’s rights.

Frequently Asked Questions

1. Does patent interference still exist under current U.S. patent law?

Yes, but only for patents or applications with effective filing dates before March 16, 2013. Newer applications are governed by the first-to-file system.

2. Who decides patent interference disputes?

The Patent Trial and Appeal Board (PTAB) oversees the process, with panels of technically trained judges reviewing evidence and arguments.

3. What is the difference between patent interference and derivation?

Patent interference decides who invented first under the old system, while derivation proceedings decide whether one party improperly derived the invention from another.

4. How long does a patent interference take?

Timelines vary, but proceedings often last one to two years, depending on discovery, motion practice, and appeals.

5. Can a patent interference decision be appealed?

Yes. Decisions can be appealed to the U.S. Court of Appeals for the Federal Circuit, which has authority to review PTAB’s conclusions.

If you need help understanding patent interference, you can post your legal need on UpCounsel's marketplace. UpCounsel accepts only the top 5 percent of lawyers to its site. Lawyers on UpCounsel come from law schools such as Harvard Law and Yale Law and average 14 years of legal experience, including work with, or on behalf of, companies like Google, Menlo Ventures, and Airbnb.