What are special technical features in unity of invention?

Special technical features are a crucial concept in determining unity of invention. According to MPEP 1893.03(d):

“The expression special technical features is defined as meaning those technical features that define the contribution which each claimed invention, considered as a whole, makes over the prior art.”

These features are used to establish a technical relationship among the inventions. For example:

  • A key defined by certain claimed structural characteristics corresponding to the claimed features of a lock would be a special technical feature.
  • The technical relationship must involve at least one common or corresponding special technical feature among the inventions.

Examiners use these special technical features to determine whether multiple inventions form a single general inventive concept, thus meeting the unity of invention requirement.

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Tags: patent applications, PCT, special technical features, unity of invention