Legal Dictionary

reduction to practice

Legal Definition of reduction to practice

See also

Definition of reduction to practice

Further reading

In United States patent law, the reduction to practice is a concept meaning the embodiment of the concept of an invention. The date of this embodiment is critical to the determination of priority between inventors in an interference proceeding.

Conception is the "formation in the mind of the inventor, of a definite and permanent idea of the complete and operative invention, as it is hereafter to be applied in practice." Hybritech Inc. v. Monoclonal Antibodies, Inc., 802 F.2d 1367, 1376 (Fed. Cir. 1986) (quoting 1 Robinson On Patents 532 (1890))

The embodiment of an invention can either be:

  • Actual reduction to practice: "[R]equires that the claimed invention work for its intended purpose." Brunswick Corp. v. U.S., 34 Fed. Cl. 532, 584 (1995).
  • Constructive reduction to practice: "[O]ccurs upon the filing of a patent application on the claimed invention." Brunswick Corp. v. U.S., 34 Fed. Cl. 532, 584 (1995).
  • "Simultaneous conception and reduction to practice": "In some instances, such as the discovery of genes or chemicals, an inventor is unable to establish a conception until he has reduced the invention to practice through a successful experiment." The Regents of the University of California v. Synbiotics Co., 849 F.Supp. 740, 742 (S.D.Cal., 1994) (citing Amgen, Inc. v. Chugai Pharmaceutical Co., Ltd., 927 F.2d 1200, 1206 (Fed. Cir. 1991)). The court will apply this doctrine in so-called "unpredictable arts" such as biology and chemistry where the invention is a "biologically active composition of matter," also called a "bio-chemical substance."

Some types of evidence

In addition to inventor's notebook, several additional kinds of evidence can be used to establish an earlier priority date.

- Working model

A "working model" is usually a strong evidence to demonstrate actual reduction to practice. Unlike patent models of the 18th and 19th century, a working model is no longer a requirement of the U.S. patent law. However, if the inventor builds a working model for testing and for displaying to potential buyers, it can also be used to prove an earlier than filing priority date.

- Disclosure Document Program

The Disclosure Document Program (DDP) was a USPTO program that allowed an inventor to file a preliminary description of his/her invention. The program was discontinued by the USPTO as of February 1, 2007, in favor of filing a provisional application. The USPTO says:

    A provisional application for patent provides more benefits and protections to inventors than a disclosure document and can be used for the same purposes as a disclosure document if necessary. . . .A non-provisional application must be filed within twelve months of the filing date of a provisional patent in order for the inventor to claim the benefit of the provisional application....[1]


  1. USPTO Website


  1. Wiktionary. Published under the Creative Commons Attribution/Share-Alike License.


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2.     landed property
3.     lex situs
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