What is the difference between ‘conception’ and ‘reduction to practice’ in a 37 CFR 1.131(a) affidavit?

In the context of a 37 CFR 1.131(a) affidavit, ‘conception’ and ‘reduction to practice’ are two distinct stages of invention:

• Conception is the formation in the inventor’s mind of a definite and permanent idea of the complete and operative invention.
• Reduction to practice can be either actual (physically creating the invention) or constructive (filing a patent application).

MPEP 715.07 explains:

In general, 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 thereafter to be applied in practice. Conception is established when the invention is made sufficiently clear to enable one skilled in the art to reduce it to practice without the exercise of extensive experimentation or the exercise of inventive skill.

If only conception is shown before the reference date, the affidavit must also demonstrate diligence in reducing the invention to practice from just before the reference date until actual reduction to practice or filing of the application.

To learn more:

• 37 CFR 1.131(a)
• conception
• reduction to practice
• invention stages

To learn more:

• 37 CFR 1.131(a)