What is the examiner’s burden of proof for means-plus-function limitations?

According to MPEP 2182, when applying prior art to a means-plus-function limitation, the examiner has specific burdens of proof:

• The examiner must show that the prior art element performs the identical function specified in the claim.
• If the prior art only teaches identity of function, the examiner carries the initial burden of proof for showing that the prior art structure or step is the same as or equivalent to the structure, material, or acts described in the specification.
• If the prior art reference teaches the identical structure or acts but is silent about performing the claimed function, the examiner must provide a “sound basis for believing” that the prior art structure inherently performs the same function.

The MPEP states: “The examiner must provide a ‘sound basis for believing’ that the prior art structure or acts would be capable of performing the claimed function.” This requirement ensures that examiners thoroughly analyze the prior art before rejecting a claim with a means-plus-function limitation.

To learn more:

• means-plus-function
• examiner burden
• prior art
• patent examination