Patent claims drafted by patent attorneys can sometimes be
difficult to read, but there is good reason. Every word put in (or
left out of) a patent claim can have a significant legal impact. A
recent US court decision highlights just how important it is to get
the wording right.
A particular patent claim in Silicon Graphics, Inc. (SGI) v.
ATI Techologies, Inc Nos. 08-1334, -1353 (Fed. Cir. June 4,
2010) defined a computer system having a component utilising
"a rasterization process which operates on a floating point
format" ('floating point' is a particular way of
representing numbers in a computer). The infringement decision in
this case turned on the interpretation of the word
The ATI product accused of infringing the patent did have a
component which performed a "rasterization process."
However, the rasterization process in the ATI product used both
'floating point' numbers and 'fixed point'
numbers (a different number format which was not mentioned in the
patent claim). The question for the court was whether this product
still infringed the wording of the patent claim, by using both
At first instance, the District Court held that the ATI product
did not operate in a floating point format "as a whole",
and so found that the patent was not infringed.
However, on appeal, the Federal Circuit overturned this
"The use of the indefinite
article "a" in the claim, when coupled with the list of
processes provided in the specification, makes it clear that the
claims' references to "a rasterization process"
means "one or more rasterization processes."
The limitation "a rasterization process which operates on a
floating point format" therefore means that "one or more
of the rasterization processes (e.g., scan conversion, color,
texture, fog, shading) operate on a floating point format....
Nowhere does the specification teach that all rasterization
processes must operate on a floating point format."
Accordingly, it was held that as long as there was one
rasterization process using 'floating point' numbers
(even if different number formats were also used), the claim would
This case highlights the importance of engaging with your
attorney to get the claim wording right, and ensure your product is
The content of this article is intended to provide a general
guide to the subject matter. Specialist advice should be sought
about your specific circumstances.
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