Doctrine of Equivalents
Definition - What does Doctrine of Equivalents mean?
The doctrine of equivalents is a law relating to patents, wherein a person tries to market a product that is equivalent to a product already patented. They could do this by substituting one step of the process for something that is equivalent to the process within the patent – but using a different material. In that case, the person would be found in breach of patent and copyright law.
Justipedia explains Doctrine of Equivalents
If a process is patented that is made up of several steps, one of which has alternatives that could be substituted to create the same effect, once a person patents their process, it is illegal for another person to substitute one step to be different from the patent holder.
Essentially, this doctrine ensures that people do not review all patents and then figure out where one alternative step could have been integrated to produce the same effect, and try to market a product based on that change.