Legal Definitions - equivalents doctrine

The equivalent doctrine is a legal theory used in patent law to determine if a product or process infringes on a patent even if it falls outside the literal scope of the patent claims. This doctrine was created to prevent parties from avoiding liability for patent infringement by making trivial changes to avoid the language of the patent claims.

For example, if a patent claims a product with a specific element, and another product has a similar element that performs the same function in the same way to get the same result, it may be considered an infringement under the equivalent doctrine.

However, the doctrine of prosecution-history estoppel may limit the use of the equivalent doctrine if the patentee voluntarily amended the claim.

Other legal doctrines include the doctrine of estates, which explains that a person cannot own land but can only own an estate in it for a specific period of time, and the doctrine of necessaries, which holds a parent or spouse liable for goods or services required for sustenance, support, or healthcare for their child or spouse.