Legal Definitions - inherency doctrine

The inherency doctrine is a principle in patent law that helps determine if an invention is truly new and therefore eligible for patent protection. It addresses situations where a feature or characteristic of an invention, even if not explicitly described in existing public knowledge (known as "prior art"), is considered to be present because it is an unavoidable and natural consequence of that prior art, and an expert in the relevant field would recognize it.

This doctrine serves two primary purposes:

• Preventing patents on old inventions: It stops individuals from obtaining a patent on an invention that already exists by simply claiming a feature that is inherently present in the older invention and would have been obvious to someone skilled in that field.
• Allowing patents on new discoveries: Conversely, it can allow for the patenting of a discovery related to an existing product or process if a previously unrecognized or unappreciated inherent property is identified, and that property was not known to be present by experts in the field at the time of the prior art.

Here are some examples illustrating the inherency doctrine:

• Example 1: Preventing a patent on an inherent characteristic

  Imagine a patent from the 1970s describing a specific type of insulated beverage container, detailing its materials and construction. Decades later, a new inventor attempts to patent "a beverage container that keeps drinks cold for extended periods," claiming this prolonged cooling as a novel feature. If it can be demonstrated that the materials and design described in the 1970s patent *necessarily resulted* in the container keeping drinks cold for that extended period, and experts in thermal engineering would have understood this to be an unavoidable property of such a design, then the prolonged cooling is considered inherent. The inherency doctrine would prevent the new patent because the cooling capability, though not explicitly highlighted in the 1970s patent, was an inherent and known property of the existing container.

• Example 2: Patenting a newly discovered inherent property

  Consider a common industrial lubricant, "Lubricant Z," which has been widely used for decades to reduce friction in machinery. Its chemical composition and primary function are well-established. A research team later discovers that Lubricant Z, when exposed to certain frequencies of light, also exhibits a previously unknown and highly effective property as a sterilizing agent against specific bacteria. This sterilizing property was always present due to its inherent chemical structure, but no one had ever recognized or appreciated it, nor was it obvious to a skilled chemist. Under the inherency doctrine, the discovery of this new, unappreciated sterilizing property, and its specific application, *could* be patentable. Even though Lubricant Z existed, its inherent sterilizing capability was not "known" or appreciated by those skilled in the art as part of its prior use.

• Example 3: An obvious inherent outcome

  A prior art patent describes a method for manufacturing paper from wood pulp, which involves a specific process of grinding, mixing with water, and pressing. A new inventor applies for a patent on "a paper manufacturing process that produces wastewater containing wood fibers," claiming the generation of such wastewater as a novel step. The inherency doctrine would apply here. It is an unavoidable and natural consequence of processing wood pulp with water to create paper that wastewater containing wood fibers will be produced. Any person skilled in the art of paper manufacturing would know this. Therefore, the production of this type of wastewater is an inherent feature of the prior art process and cannot be claimed as a new, patentable invention.