Legal Definitions - doctrine of substantial equivalents

The doctrine of substantial equivalents is a principle in patent law that prevents others from making minor, insubstantial changes to a patented invention to avoid infringement. It allows a patent holder to claim infringement even if a competing product or process does not *literally* include every single element of the patented invention.

Under this doctrine, an invention can still be considered infringing if it performs substantially the same function, in substantially the same way, to achieve substantially the same result as the patented invention. This ensures that the scope of a patent is not limited solely to its exact wording, but also covers variations that are essentially identical in their operation and outcome, thereby protecting the true essence of the invention.

Here are some examples illustrating the doctrine of substantial equivalents:

• Example 1: Mechanical Device

  Imagine a company holds a patent for a unique bicycle pedal that uses a specific type of spring-loaded plastic clip to secure a rider's shoe. A competitor then designs a very similar pedal that uses an identical spring mechanism but replaces the plastic clip with a durable rubber clip. If the rubber clip performs the exact same function (securing the shoe), in the same way (spring-loaded mechanism), to achieve the same result (a secure connection between shoe and pedal) as the patented plastic clip, the competitor's pedal could be found to infringe under the doctrine of substantial equivalents. The change from plastic to rubber is considered an insubstantial alteration.

• Example 2: Chemical Process

  Consider a patent granted for a new industrial process to create a specific type of flame-retardant material. The patent specifies using a particular catalyst, "Catalyst A," at a temperature of 150 degrees Celsius. A rival company develops a process that uses "Catalyst B," which is chemically very similar to Catalyst A and performs the identical catalytic function in the same chemical reaction, yielding the same flame-retardant material. Even if Catalyst B is not literally Catalyst A, if it is shown to be a known equivalent that functions identically in the patented process, the rival company's process could be deemed an infringement under the doctrine of substantial equivalents. The substitution of an equivalent catalyst would be seen as an insubstantial change.

• Example 3: Software Algorithm

  Suppose a software company patents an algorithm for efficiently compressing large video files, which involves a specific mathematical transformation of pixel data. A competitor then develops their own video compression software that uses a slightly different, but mathematically equivalent, transformation to achieve the same compression ratio and processing speed. While the competitor's algorithm doesn't use the *exact* mathematical formula described in the patent, if it performs the same function (data compression), in a substantially similar way (mathematical transformation of pixel data), to achieve the same result (efficiently compressed video files), it could be found to infringe the patent under the doctrine of substantial equivalents. The minor mathematical variation would be considered an insubstantial change that does not alter the core inventive concept.