This section outlines the meaning of 'reduction to practice'. Constructive reduction to practice requires compliance with 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph.

This section also discusses the two prong test that is used to establish actual reduction to practice. The nature of testing which is required to establish a reduction to practice depends on the particular facts of each case. Also discussed is the three prong test that must be met before a non-inventor's recognition of the utility of the invention can inure to the benefit of the inventor.

In an interference proceeding, the device reduced to practice must include every limitation of the count. In addition, utility for the invention must be known at the time of the reduction to practice. Lastly, a probable utility does not establish a practical utility, which is established by actual testing or where the utility can be “foretold with certainty.”

• Review Ed9 10.2019: 2138.05

This section discusses the meaning of 'reasonable diligence' in relation to pre-AIA 35 U.S.C. 102(g). It covers the critical period for establishing diligence between one who was first to conceive but later to reduce to practice the invention.

The entire period during which diligence is required must be accounted for by either affirmative acts or acceptable excuses. Work relied upon to show reasonable diligence must be directly related to the reduction to practice

The diligence of attorney in preparing and filing patent application inures to the benefit of the inventor. The end of the diligence period is marked by either actual or constructive reduction to practice.

• Review Ed9 10.2019: 2138.06