Actual reduction to practice

Actual reduction to practice requires that the inventor "prove that: (1) he constructed an embodiment or performed a process that met all the limitations. . . and (2) he determined that the invention would work for its intended purpose." Whether actual testing is required to prove the invention works for its intended purpose depends on the character and complexity of the invention and the problem it addresses. Some inventions may be "so simple and their purpose and efficacy so obvious that their complete construction is sufficient to demonstrate workability." "[R]eduction to practice cannot be established nunc pro tunc;" rather, "[t]here must be contemporaneous recognition and appreciation of the invention represented by the counts."