Chapter §5.07 Scope of the Best Mode Disclosure Versus Scope of the Claims

• Jurisdiction: United States

§5.07 Scope of the Best Mode Disclosure Versus Scope of the Claims

The two-part Chemcast analysis does not address all aspects of best mode compliance. Yet another ambiguous area of best mode analysis concerns the scope of the best mode disclosure obligation vis-à-vis the scope of the claims. Because 35 U.S.C. §112, ¶1, uses the seemingly broad phrase "best mode of carrying out the invention," some Federal Circuit decisions suggest that the best mode obligation may extend to elements of an invention even if those elements are not recited in the claims.

For example, in Dana Corp. v. IPC Ltd. Partnership,⁹⁹ the Federal Circuit invalidated the patent in suit, which claimed an elastomeric valve stem seal of the type used in automobile engines. The patent failed to disclose a fluoride surface treatment that the inventor's test reports indicated was "necessary to [the] satisfactory performance of [the] seal."¹⁰⁰ The appellate court held that the best mode obligation had not been satisfied, despite the fact that this fluoride surface treatment was not recited in the claims of the patent, which were directed to the seal itself.

Reliance on these earlier, more expansive best mode decisions should proceed cautiously. More recently, the Federal Circuit has clarified that "an inventor need not disclose a mode for obtaining unclaimed subject matter unless the subject matter is novel and essential for carrying out the best mode of the invention."¹⁰¹

This more limited disclosure obligation is illustrated by Eli Lilly & Co. v. Barr Labs., Inc.,¹⁰² in which the patent in suit claimed the chemical compound fluoxetine hydrochloride and a method of administering the compound to block the uptake of the monoamine serotonin in patients suffering from anxiety or depression. The written description of the patent identified p-trifluoromethylphenol as a starting material from which the claimed compound could be made, but did not disclose the process by which the patentee synthesized the starting material. The Federal Circuit rejected the accused infringer's contention that the patent did not satisfy the best mode requirement because it did not disclose the patentee's method of synthesizing the starting material, a method that the patentee considered proprietary and commercially advantageous. Although the best mode for developing the claimed compound involved the use of this starting material, the Federal Circuit explained, the patent did not "cover" it.¹⁰³ Moreover, the unclaimed...