Claim interpretation
1.    Unlike copyrights or trademarks you have to claim up front.
a.    Seems like this should make life easier by explicitly delineating rights.
b.    In reality, it isn’t.
(A)    Difficult to write claims. Must be narrow enough to avoid prior art,  broad enough to get rights to things you don’t know yet, plus racing aspect.
(B)    Many patents aren’t litigated, so hard work is in vane.
2.    General rule: Look at express language of claim but interpret in light of a lot of things.
a.    Intrinsic evidence: Best evidence, includes drawings, specification and prosecution history.
b.    Extrinsic evidence
(A)    Dictionaries and treaties: Definitely can use them, second-best evidence.
(B)    Courts have allowed articles in the field, testimony of inventor as to what she accomplished, expert testimony though these things are weighted less then intrinsic evidence and dictionaries.
c.    Any evidence can be used for court’s own education.
3.    Comparing claim to accused process (Autogiro)
a.    Literal Infringement: Construe claim then ask is every element and every limitation on every element in accused device.
b.    Doctrine of Equivalents: May broaden patentee’s right to exclude somewhat beyond the literal language. thus, courts may broaden and narrow patent rights to give the patentee something different than what is literally claimed. Courts cannot, however, broaden or narrow the actual claims.
c.    Specification: Courts refer to it do define words and phrases used in claims, but limitations may not be “read into” the claims from the specification. Fuzzy line, see Unique Concepts
d.    Reverse Doctrine of Equivalents