When drafting patent claims, even minor differences in wording can be important.  In 2006, I attended a seminar given by Steve Shear of Silicon Valley Seminars, http://www.patentseminars.com, called "Patents and Patent Claim Drafting."  One of the points taught was that the use of "coupled to" was risky.  That was because reciting that element A is "coupled to" element B might be read as requiring that element A be directly connected to element B.  It is safer to recite that element A is "coupled with" element B, since that more clearly recites that element A may be indirectly connected with element B.

In Bradford Co. v. Conteyor North America, Inc., 2010 U.S. App. LEXIS 8869 (Fed. Cir. April 29, 2010) the Federal Circuit construed the claim terms "coupled to."  The U.S. District Court had granted summary judgment of noninfringement to defendant Conteyer NA relying on its claim construction that "coupled to" required a direct connection between two recited claim elements.  The relevant independent claims recited a "dunnage structure" that was "coupled to" a "frame" or "side structure."  Id. *5-6.  The Federal Circuit reversed the district court's claim construction, holding that the claim terms allow "an indirect coupling of the dunnage to the frame."  Id. *19.  But this opinion should not be read as holding that "coupled to" will always be read to allow an indirect connection.  On the contrary, there were specific circumstances in this case that caused the Federal Circuit to construe "coupled to" as allowing an indirect connection.

The Federal Circuit began its analysis by citing Phillips v. AWH Corp., 415 F.3d 1303, 1314 (Fed. Cir. 2005) (en banc) for the proposition that the starting point for construing claims is the language of the claims themselves.  But it was not the language of the contested independent claims that carried the day.  Instead, it was the language of a dependent claim and the doctrine of claim differentiation.  The Court noted that, "Dependent claim 10 of the '096 patent recites a dunnage structure that is coupled to rails which in turn are coupled to the side structures."  Id.  Because dependent claim 10 recited one example of indirect attachment, under the doctrine of claim differentiation, the independent claims were "presumed to be broader to allow for other types of indirect attachments.  Id. *20 citing Comark Commc'ns, Inc. v. Harris Corp., 156 F.3d 1182, 1186 (Fed. Cir. 1998).  The doctrine of claim differentiation creates a presumption that different claims have different scope.  Id.

While the presumption created by claim differentiation "is not a conclusive basis for construing claims," in this case there was nothing in either the specification or the prosecution history to overcome the presumption.  Id.  On the contrary, the specification provided examples of indirect connection, both in the figures and in the written description.  In holding that "coupled to" allows for an indirect connection, the Federal Circuit noted "the clear disclosure in the patent ***."  Id.  Thus, even in light of this opinion, it is still wiser to use the claim terms "coupled with" rather than "coupled to" if coverage for indirect connection of claim elements is desired.