ISSUE:
Whether the substitution of a similar material not claimed in the patent itself would save the Defendants from being held liable for infringements?
Does the doctrine of equivalents apply to chemical equivalents in compositions or to mechanical equivalents in devices?
RULE:
The doctrine of equivalents is a legal rule that allows a court to hold a party liable for patent infringement even though the infringing device or process does not fall within the literal scope of a patent claim, but nevertheless is equivalent to the claimed invention.
The doctrine of equivalents is applied to chemical equivalents in compositions or to mechanical equivalents in devices.