What are the requirements for a negative limitation to be considered definite?

For a negative limitation to be considered definite, it must clearly set forth the boundaries of the patent protection sought. According to MPEP 2173.05(i), the key requirement is that the claim complies with 35 U.S.C. 112(b), which requires the claims to particularly point out and distinctly claim the subject matter of the invention.

The MPEP provides examples of definite negative limitations:

• A claim reciting “said homopolymer being free from the proteins, soaps, resins, and sugars present in natural Hevea rubber” was considered definite because each recited limitation was definite. (In re Wakefield)
• The negative limitation “incapable of forming a dye with said oxidized developing agent” was found definite because the boundaries of the patent protection sought were clear. (In re Barr)

These examples illustrate that negative limitations can be definite if they clearly exclude specific elements or characteristics, thereby defining the scope of the invention.

To learn more:

• negative limitations
• patent claims
• claim definiteness
• 35 U.S.C. 112(b)
• MPEP