Phillips v. AWH Corp. 415 F.3d 1303 (Fed. Cir. 2005) Phillips invented a corrugated steel wall that was useful for prisons. He obtained a patent. Phillips then sued AWH who made a similar product. Phillips walls were filled with 'baffles'. The 'baffles' shown in Phillips' patent were a different shape from the baffles that AWH was using in their product. fyi, AWH's baffles were used to stop bullets from going through the walls. Basically, AWH had argued that Phillip's 'baffles' weren't designed deflect bullets at all, they just help the wall stand up. AWH said that the word 'baffle' is defined in the dictionary as something that 'deflects something', therefore Phillip's wall didn't actually have 'baffles' at all. Phillips argued that architects used the word 'baffle' differently, and so his wall had 'baffles'. The Trial Court found for AWH. Phillips appealed. The Trial Court found that, in light of to Marksman v. Westview Instruments, Inc. (517 U.S. 370 (1996)), it was the Judge who was to construe the meaning of the terms in the patent specification. The Judge looked only at the specification, and found that the "baffles" must be angled to deflect bullets. Under this construction, Phillips could not prove infringement. The Appellate Court reversed. Phillips argued that the Trial Judge should not have placed so much weight on the wording in the specification when construing the claim construction. However, the Appellate Court found that "entirely appropriate for a court, when conducting claim construction, to rely heavily on the written description for guidance as to the meaning of the claims." The Court noted that 5 U.S.C. § 112 ¶1, says that the "specification necessarily informs the proper construction of the claims." Courts should also look at the other claims of the patent to see if you can construe meaning of any terms in the ambiguous claim. The canon of claim differentiation says that courts should not construe to claims to have the same meeting. The Court found that looking at prosecution history is less useful because of a lack of clarity in comparison to the specification. The Court found that extrinsic evidence (like dictionaries) is less useful because here is no guarantee that a term is used in the same way in a treatise or dictionary as it is by the patentee. Although dictionary and treatise definitions may have value when it comes to better understanding the underlying technology, they may only be used to construe clams when the definition does not contradict definitions found in or ascertained from the specification. Although the Court agreed with the way the Trial Court approached the problem, they disagreed with the Trial Court's conclusion that the intrinsic evidence contained in the specification made it impossible for AWM to be infringing on Phillips patent, so they reversed on those grounds. Basically, this case said that when a judge is called on to construe what the words in a patent claim mean, they should perform a detailed analysis of the patent specification (as well as the other claims in the patent), and not rely very heavily on extrinsic evidence (like dictionary definitions) or procedural history.