What constitutes a reduction to practice in the context of the on-sale bar?
In the context of the on-sale bar, reduction to practice typically requires demonstrating the practical utility of an invention under actual working conditions. The MPEP states:
Actual reduction to practice in the context of an on-sale bar issue usually requires testing under actual working conditions in such a way as to demonstrate the practical utility of an invention for its intended purpose beyond the probability of failure, unless by virtue of the very simplicity of an invention its practical operativeness is clear.
(MPEP 2133.03(c))
It’s important to note that the invention doesn’t need to be ready for satisfactory commercial marketing to trigger the on-sale bar. The focus is on demonstrating that the invention works for its intended purpose.
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