Controlling Patent Prosecution History

[Excerpt] “One of the most salient effects of patent prosecution history arises in the context of the doctrine of equivalents. Under that doctrine, although patent claims may be found to be broader than their literal scope, territory surrendered during prosecution cannot be encompassed as equivalent. Nor can territory forfeited by initial failure to claim be captured under the doctrine of equivalents. Most attorneys who prosecute applications are apt to be aware of such problems and to take measures to avoid them.”