Doctrine of equivalence

This doctrine expresses that when determining the scope of a patent (or utility model), a claimed feature may be replaced by a different one that performs the same or substantially the same function in the same or substantially the same manner with the same or substantially the same effect. In a recent utility model case, the Metropolitan Appeal Court explained that equivalency may not be extended to features that were not available before the priority date due to the lower level of the state of the art.