From the point of view of patentability, how specialized is “the art” of the “person having ordinary skill in the art” (PHOSITA)?

For example, if I attempt to patent a widget that connects between the thingumajig and the doohickey in a marine engine, it may be obvious to a marine engine designer, curious to an auto engine designer, and baffling to a random mechanical engineer. How do patent examiners determine how specific the field of an invention is?


PHOSTIA is a hypothetical person having omniscient knowledge of publications in the field as of the day of filing but ordinary skill.

During examination at the USPTO what level this person might be is usually glossed over. In court it becomes an issue of debate. Each side tries to convince the judge that their view of the level of expertise need to be a PHOSITA is correct. One side argues it needs to be a PH.D. in biology to design rat traps the other that only one shop class with no high school diploma is the correct level for a PHOSITA.


A person who is familiar with thingumajig and doohickey - the person needs to be familiar with the prior art (as this is the current state of the art), so an engineer, who has never seen a doohickey would not be skilled in that art.

So it is rather specific.

As another example: If you make a new mouse trap, then the art is "making traps for animals". If someone, who is skilled in making traps for animals reads all prior art about mouse traps, would he come easily to the conclusion, how to make the new mouse trap from the prior art of mouse traps and his skill?

  • In that example the range of publications the PHOSITA is hypothetically aware of would be broader than just mouse traps. If the examiner says "Look at reference X, a PHOSITA trying to solve the problem would know about it" you can argue that X should be excluded as outside the field and is also not "analogous art". It is usually a hard argument to win.
    – George White
    Aug 7 '14 at 21:18

Building on what George said -- there will be some argument about this, and it is a good question. But generally, the PHOSITA will be somewhat specific to the field. There have been cases where the PHOSITA was described narrowly enough that only a few people on the planet fit the definition -- you just have to argue that it's a highly specialized field, and that that is the appropriate light in which to view the situation. Often times you will see that PHOSITA will be expected to have a Ph.D., but sometimes not.

So... really, the best answer to your question is that there is no general answer. It's a good question. Argue it case-by-case. You won't win every time -- examiners have experience and precedent to work with -- but you can certainly try. Good luck.

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