Inventorship: What You Need To Know To Avoid Problems

  • October 24, 2017

By: Peter C. Lando

The concept of inventorship appears simple to some, but in many situations it can be difficult to properly determine who, among the individuals contributing to an invention, qualifies as an inventor. The question of inventorship has been a challenging issue since the first patent laws were enacted. It is an important question to get right, because misnaming inventors in a patent application may render a resulting patent unenforceable.

To better understand inventorship, there are three basic principles to know:

  1. One must first identify the “invention” to be able to identify the “inventors.”
  2. The “invention” is defined by the patent claims.
  3. An “invention” requires conception and reduction to practice.

An invention is any new and useful process (way of doing or making things), machine, manufacture, design, or composition of matter, or any new and useful improvement thereof, or any variety of plant, which is or may be patentable under the patent laws of the United States. To be a named inventor, one must have contributed to the conception of an invention, and the contribution must be more than routine engineering skill or supervision.

Joint inventors may apply for a patent jointly even if (a) they did not physically work together or at the same time, (b) each did not make the same type or amount of contribution, and/or (c) each did not make a contribution to the subject matter of every claim in the patent application.


A contribution to the conception of an invention is the touchstone of inventorship. Conception is the completion of the mental part of invention. To know who conceived an invention one must know what conception is – which can get pretty muddy in practice. Conception of an invention requires two steps: it must exist and it must be complete. Persons involved in both steps are inventors.

  1. Existence – when a definite and permanent idea of an operative invention including every feature of the subject matter sought to be patented is known.
  2. Completeness – when one of ordinary skill in the art could construct the apparatus, perform the process, or make the composition without unduly extensive research or experimentation.

Note that conception may exist and be complete even though experimentation continues, for example when a concept is proven yet modifications are still being made, e.g., for optimization. On the other hand, conception may not exist where the viability of the concept is yet uncertain. In some instances, however, corroborating evidence apart from the mind of the inventor may be useful in distinguishing whether the conception is complete.

Reduction to Practice

After conception, invention is deemed to have occurred when the inventor(s) have reduced it to practice. Reduction to practice occurs in one of two ways: actual or constructive reduction to practice.

  1. Actual – sufficiently developing and testing the invention to show that it will work for its intended purpose.
  2. Constructive – filing of a patent application describing and claiming the invention sufficiently to teach one of skill in the art how to practice the invention.

It should be noted that participation in the reduction to practice of the invention, without more, does not make an individual an inventor. Mere technicians, lab workers, software developers, and the like, are not inventors if they are only following the direction of others who conceived of the complete conception. On the other hand, if a technician conceives of a breakthrough solution during the reduction to practice, and if the breakthrough becomes part of the invention as reflected in the claims, then the technician is a properly named inventor. In other words, someone participating in the reduction to practice must also contribute to the final, complete conception to be an inventor.

As a final note, if a date of invention is important, U.S. patent practice holds that the date of invention is the date of conception only if the inventor(s) diligently work toward a reduction to practice. Otherwise, the date of invention is the date of reduction to practice, whether actual or constructive.


The touchstone of being an inventor is in contributing to the conception of an invention. One who applies ordinary skill to test, optimize, make a prototype, or manage the invention is not an inventor unless he/she contributed to its conception.

It is of utmost importance to identify the proper inventors, as any patent without proper inventorship may be at risk of being unenforceable. It is not often clear at the outset of invention how things will progress, and human memory gets fuzzy. Thus it is important to keep good records – of individuals’ contributions along the way, and of efforts and diligence to reduce the invention to practice – for later reference in determining the proper inventorship.

The boundaries of inventorship are often unclear, and in many cases it is desirable to seek the opinion of qualified intellectual property counsel in determining who are the properly named inventors.



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