Person Having Ordinary Skill in the Art (PHOSITA): The Ultimate Guide

LEGAL DISCLAIMER: This article provides general, informational content for educational purposes only. It is not a substitute for professional legal advice from a qualified attorney. Always consult with a patent_attorney for guidance on your specific legal situation.

Imagine you're trying to fix a complex modern car engine. To you, a casual driver, the web of wires and sensors is a complete mystery. You might try something simple, like checking the battery. But a skilled, experienced mechanic sees things differently. They understand how the fuel injector, the spark plugs, and the computer system all work together. A solution that seems like a stroke of genius to you—like combining two specific sensors to solve a known stalling issue—might be considered a logical, even obvious, next step for them. In the world of inventions and patents, this skilled mechanic is the Person Having Ordinary Skill in the Art, or PHOSITA. The PHOSITA is the single most important concept in determining whether your invention is truly innovative enough to deserve a patent. This imaginary legal figure isn't a genius, but they aren't a novice either. They are the benchmark—the reasonable, competent professional in your specific field—against whom the U.S. government measures your invention. If the PHOSITA would have found your invention “obvious,” you likely won't get a patent. Understanding this concept is absolutely critical for any inventor, entrepreneur, or small business owner hoping to protect their ideas.

• Key Takeaways At-a-Glance:
  • A Legal Measuring Stick: The person having ordinary skill in the art is a hypothetical, legal standard, not a real individual, used by the united_states_patent_and_trademark_office (USPTO) and courts to evaluate if an invention is an “obvious” combination of existing technologies.
  • The Gatekeeper to a Patent: The PHOSITA's main role is to determine non-obviousness, one of the three core requirements for patentability, alongside novelty and utility. If your invention would have been obvious to the PHOSITA at the time you created it, it cannot be patented under U.S. law.
  • Your Field Defines Your PHOSITA: Who the person having ordinary skill in the art is depends entirely on the technology. A PHOSITA in software engineering has a completely different skillset and knowledge base than a PHOSITA in biotechnology or mechanical engineering.

The idea of judging an invention against the knowledge of a skilled craftsperson isn't new. Its roots trace back to the very foundations of American patent law. Early court decisions struggled with how to draw a line between a truly inventive leap and a simple, skillful improvement that any competent worker in the field might make. The landmark 1850 Supreme Court case, `hotchkiss_v._greenwood`, was a critical turning point. The case involved a patent for using a common porcelain or clay doorknob on a metal shank. The Court invalidated the patent, arguing that the substitution of materials didn't involve any more “ingenuity and skill” than that possessed by an “ordinary mechanic acquainted with the business.” This was the birth of the concept: an invention must be more than just good workmanship; it must involve a spark of ingenuity beyond the everyday problem-solving of a skilled worker. This “ordinary mechanic” standard evolved over the next century, but it was formally codified and given its modern name in the Patent Act of 1952. This comprehensive overhaul of U.S. patent law introduced the explicit requirement of “non-obviousness” and established the “person having ordinary skill in the art” as the official legal standard for this evaluation.

The entire modern concept of the PHOSITA is anchored in a single, powerful section of the U.S. Code governing patents. This law, `35_u.s.c._103`, states:

“A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains.”

Let's break that down into plain English:

• “…not identically disclosed…“: This means that even if your invention is technically new (novel), it might still be unpatentable.
• ”…prior art…“: This refers to the entire body of public knowledge that existed before you filed your patent application. It includes previous patents, scientific papers, products, and public demonstrations. See our full guide on `prior_art`.
• ”…obvious…“: This is the key test. It asks whether your invention is just a logical, predictable next step based on that existing prior art.
• ”…to a person having ordinary skill in the art…“: This is the crucial phrase. It establishes who gets to make that judgment call. The question is not whether the invention is obvious to a judge, a jury, or the general public. It is only about whether it would have been obvious to this very specific, hypothetical expert.

This statute makes the PHOSITA the central character in the drama of almost every patent dispute.

The PHOSITA is not a real person, but a legal construct. To understand who this “person” is, it's helpful to compare them to others. The PHOSITA occupies a middle ground, possessing a complete and perfect knowledge of all relevant prior art in their field, but without any inventive spark or creativity of their own.

What this means for you: When evaluating your invention, you cannot think like yourself, the inventor. You must step into the shoes of the PHOSITA—a cautious, un-creative but highly knowledgeable technician—and ask, “Would this person, knowing everything that was publicly known, have seen my invention as a logical next step?”

Simply saying an invention is “obvious” is subjective. The Supreme Court recognized this and, in the monumental 1966 case `graham_v._john_deere_co.`, established a mandatory, four-part framework for analyzing obviousness through the eyes of the PHOSITA. These are known as the Graham Factors. A patent examiner at the USPTO and a judge in court must consider these factors.

The entire analysis is a factual inquiry into the state of the art at the time of the invention, viewed from the perspective of the PHOSITA.

Before you can analyze anything else, you must first define the PHOSITA. Who is this person? This is a critical, foundational step. Courts and the USPTO look at several sub-factors to build a profile of the PHOSITA for a given invention:

• Educational Level: What is the typical education of inventors and workers in this specific field? Is it a high school diploma, a Bachelor's degree in engineering, or a Ph.D. in molecular biology?
• Type of Problems Encountered: What are the common, day-to-day challenges in this industry?
• Prior Art Solutions: What solutions did the prior art offer to solve these problems? The complexity of these solutions provides a clue to the skill level of the practitioners.
• Rapidity of Innovation: Is this a slow-moving field (e.g., plow design) or a rapidly changing one (e.g., machine learning algorithms)? A PHOSITA in a fast-moving field is expected to be more sophisticated.
• Level of Sophistication of the Technology: Is the technology simple and mechanical or highly complex and electronic?

Example: For an invention related to a new smartphone app, the PHOSITA might be a person with a Bachelor's degree in Computer Science and 3-5 years of experience in mobile app development. For a new pharmaceutical drug, the PHOSITA would likely be a team of individuals, including a medicinal chemist with a Ph.D. and several years of post-doctoral research experience.

Once you know who the PHOSITA is, you must determine what they “know.” This involves a deep dive into the prior art. The PHOSITA is presumed to have read and understood everything in their field that was publicly available before the invention was filed. This includes:

• U.S. and foreign patents
• Scientific and technical journals
• Conference presentations
• Products sold or publicly used
• University theses and textbooks

The key here is relevance. The prior art must be “analogous,” meaning it's either from the same field of endeavor as the invention or, if from a different field, it's still reasonably pertinent to the particular problem the inventor was trying to solve.

This is a direct, head-to-head comparison. You must place the invention's `patent_claims` (the legally defined boundaries of the invention) side-by-side with the teachings of the closest prior art.

• What specific elements of your claim are new?
• What is the precise difference in structure, function, or result?

This step must be performed without the benefit of “hindsight bias.” Hindsight is the natural human tendency to look back at an invention and think, “Oh, of course, that was easy!” The law strictly forbids this. The analysis must be based only on the information available to the PHOSITA *before* the invention was made.

Sometimes, the technical analysis of factors 1-3 is inconclusive. This is where “secondary considerations” become critically important. These are real-world, objective clues that suggest the invention was not, in fact, obvious. They act as a guard against hindsight bias. The PHOSITA, being a non-creative type, would not have made the inventive leap, but these factors show that the invention had a real-world impact that was surprising. Strong secondary considerations can be the most persuasive evidence to overcome a rejection for obviousness. Key examples include:

• Commercial Success: If the invention became a huge commercial hit, it suggests it filled a need that others, presumably PHOSITAs, missed. (This success must be linked to the novel features of the invention, not just marketing.)
• Long-Felt but Unsolved Need: If a problem existed in the industry for years, and many tried and failed to solve it, the eventual solution is less likely to have been obvious.
• The Failure of Others: Direct evidence that other skilled individuals tried to solve the same problem and failed is powerful proof of non-obviousness.
• Skepticism by Experts: If experts in the field initially dismissed the invention as unworkable or foolish, it suggests the solution was not obvious.
• Praise and Awards: Unexpected praise from the industry or receiving prestigious awards can indicate the invention was a significant, non-obvious contribution.

Understanding the PHOSITA is not just a theoretical exercise. It's a practical tool you must use to assess your invention's strength and navigate the patent process.

Before you spend thousands of dollars on a `patent_application`, perform your own PHOSITA analysis. Be brutally honest with yourself.

1. Identify your invention's specific technical field. Be as narrow as possible. Not just “software,” but “data compression algorithms for mobile video streaming.”
2. Profile the PHOSITA. Based on that field, what is the typical education and experience level? What journals do they read? What conferences do they attend? This helps you define where to look for prior art.

1. Act like the PHOSITA. Assume you have perfect knowledge. Use patent databases (like the USPTO's and Google Patents), academic search engines (Google Scholar), and industry publications.
2. Document everything. Save copies of the most relevant patents and articles you find. These are the documents the real patent examiner will likely use against you. See our guide on how to conduct a `prior_art_search`.

1. List the key elements of your invention.
2. For each element, find where it exists in the prior art.
3. Identify your “inventive step.” What is the one thing you do differently? Is it a new combination of old parts? A new structure? A new process?
4. Ask the hard question: Is there a reason a PHOSITA, seeing all this prior art, would have been motivated to combine these elements in the way you did to achieve a predictable result? This is the core of the `ksr_international_co._v._teleflex_inc.` standard (see below).

1. Start from day one. Did you show your idea to an expert who said it wouldn't work? Document it (e.g., save the email).
2. Track your progress. If you build a prototype and it solves a problem that has plagued your industry, write down the history of that problem.
3. Record user feedback. Early positive feedback from potential customers about how your solution is unique and valuable can be powerful evidence.

1. This is not a DIY project. A registered `patent_attorney` is an expert in this analysis. They can help you perform a professional search, properly define your invention in the claims, and frame the arguments for non-obviousness in a way that will be persuasive to a patent examiner.

The modern understanding of the PHOSITA has been sculpted by several key Supreme Court decisions.

• Backstory: This case involved a patent for a spring-clamp system on a plow that allowed the shank to flex upward when it hit a rock, preventing it from breaking. Similar spring systems existed in other plows.
• The Legal Question: How should courts systematically determine if an invention is obvious under `35_u.s.c._103`?
• The Court's Holding: The Supreme Court invalidated the patent, finding the invention to be an obvious combination of known elements. More importantly, it established the mandatory four-part Graham Factors framework (Level of Skill, Scope of Prior Art, Differences, and Secondary Considerations) that is still the law of the land today.
• Impact on You: Every patent application and every patent lawsuit involving obviousness must follow the analytical framework set out in *Graham*. It provides the roadmap for the entire debate.

• Backstory: The invention was an adjustable gas pedal for cars that combined an electronic sensor with a fixed pivot point. The prior art showed many adjustable pedals and the use of electronic sensors on pedals, but not this exact combination.
• The Legal Question: Must there be an explicit “teaching, suggestion, or motivation” (TSM) in the prior art to combine known elements for an invention to be obvious?
• The Court's Holding: The Supreme Court unanimously rejected a rigid application of the TSM test. It held that the analysis should be more flexible and commonsensical. A PHOSITA, the Court argued, can apply ordinary creativity and common sense. If a technique is known to improve a device, and applying it to another similar device would yield predictable results, doing so is likely obvious.
• Impact on You: *KSR* made it somewhat easier for patent examiners to reject inventions as obvious. You can no longer simply argue that no single document suggested combining elements A and B. You must now show why that combination would not have been a common-sense, predictable step for the PHOSITA.

The PHOSITA concept is being stretched to its limits by rapidly advancing technologies.

• Artificial Intelligence: How do you define a “person” of “ordinary skill” in a field where the state of the art changes every few months? Is the PHOSITA a human programmer, or should their skill level be benchmarked against what an AI itself can produce? This is a fierce debate.
• Biotechnology: In fields like gene editing (CRISPR), the “ordinary” skill level is extraordinarily high. This can make it very difficult to patent improvements that might seem groundbreaking to the public but are considered routine and predictable steps by the small community of Ph.D.-level experts who are the relevant PHOSITAs.

Looking ahead, the legal system will have to grapple with profound questions.

• Generative AI: As AI becomes capable of “inventing” on its own, could an AI be used as the benchmark for the PHOSITA? An attorney could argue an invention is obvious by showing that a generative AI, when fed the prior art and the problem, produced a similar solution.
• The “Team of PHOSITAs”: For highly complex inventions that cross multiple disciplines (e.g., a medical device using novel materials, complex software, and biological sensors), courts are increasingly defining the PHOSITA not as a single person, but as a hypothetical research and development team with expertise in all relevant areas. This trend will likely continue, making the obviousness analysis even more complex.

• claim_(patent): The numbered sentences at the end of a patent that define the legal boundaries of the invention.
• enablement: A patent law requirement that the patent specification must teach a PHOSITA how to make and use the invention without undue experimentation.
• hindsight_bias: The cognitive error of viewing past events as having been predictable, which is strictly forbidden in an obviousness analysis.
• inventive_step: A term used in many non-U.S. patent systems that is largely synonymous with non-obviousness.
• non-obviousness: The core patentability requirement under 35 U.S.C. § 103 that an invention must not have been obvious to a PHOSITA.
• novelty: The patentability requirement that an invention must be new and not previously known to the public.
• office_action: A formal communication from a patent examiner at the USPTO, often containing a rejection of patent claims.
• patent: A government-granted exclusive right to an inventor to exclude others from making, using, or selling their invention for a limited time.
• patent_application: The set of documents filed with the USPTO by an inventor to seek a patent.
• patent_attorney: A lawyer with a specialized license to represent clients before the USPTO.
• prior_art: The entire body of public knowledge related to an invention that existed before the invention was made or its patent application was filed.
• prosecution_(patent): The process of negotiating with the USPTO from the filing of a patent application until the patent is either issued or abandoned.
• specification_(patent): The written description of the invention in a patent application.
• united_states_patent_and_trademark_office (USPTO): The federal agency responsible for examining and issuing patents.

• prior_art
• non-obviousness
• patent_application
• patent_claims
• graham_v._john_deere_co.
• ksr_international_co._v._teleflex_inc.
• 35_u.s.c._103