How do courts view negative limitations in patent claims?

Courts generally view negative limitations in patent claims as acceptable, provided they meet certain criteria. The MPEP 2173.05(i) states:

“The current view of the courts is that there is nothing inherently ambiguous or uncertain about a negative limitation.”

This represents a shift from older views where courts were sometimes critical of negative limitations. The MPEP notes that some older cases viewed negative limitations unfavorably because they defined the invention in terms of what it was not, rather than what it was. However, the current perspective is that negative limitations are acceptable as long as they clearly define the boundaries of patent protection sought.

Courts now focus on whether the negative limitation complies with the definiteness requirement of 35 U.S.C. 112(b), rather than dismissing them outright.

To learn more:

• negative limitations
• patent claims
• claim drafting
• patent law
• MPEP
• court views