What constitutes ‘unexpected results’ in patent law?

‘Unexpected results’ in patent law refer to properties or outcomes of an invention that are surprising or unanticipated based on the prior art. The MPEP states: Any differences between the claimed invention and the prior art may be expected to result in some differences in properties. The issue is whether the properties differ to such an extent that the difference is really unexpected. (MPEP 716.02)

To be considered evidence of nonobviousness, unexpected results should be:

  • Significant and practical, not just statistically different
  • Commensurate in scope with the claimed invention
  • Compared against the closest prior art

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Tags: nonobviousness, patent examination, prior art, unexpected results