Adaptive Spectrum and Signal Alignment Inc v British Telecommunications Plc

Patent claims are construed through the understanding of the skilled person, having regard to the language, context and purpose of the invention. Limitations found only in embodiments should not be imported into a claim merely because the specification’s examples contain them.

A claim to generating a parameter may encompass selecting a pre-stored value from a lookup table where that construction accords with the invention’s purpose and operation under the contemplated technical standards. Potential invalidity does not itself justify a narrower construction. An obviousness challenge also fails where the evidence leaves a material gap between the prior art’s teaching and the claimed method.

ASSIA owned two patents concerning automated management of ADSL lines. Birss J, in [2013] EWHC 3768 (Pat), held patent 790 valid and infringed by BT’s Next Generation Access system. He held patent 495 valid on a narrow construction but not infringed. Claim 1 of patent 495 would be invalid if construed more broadly.

BT appealed against the infringement finding on patent 790, including a pleading objection and numerous claim-construction issues. ASSIA appealed concerning patent 495. It contended that “generating” encompassed selecting a parameter from a lookup table and that dependent claim 6 was valid and infringed, even though claim 1 would then be invalid.

1. Disposition. BT’s appeal concerning patent 790 was dismissed. ASSIA’s appeal concerning patent 495 was allowed, and a finding that claim 6 was infringed was substituted. Floyd LJ delivered the judgment, with which Sir Stanley Burnton and Patten LJ agreed.
2. Pleading. ASSIA had complied with the order requiring it to identify the relevant passages of BT’s product and process description and had pleaded the material facts. It did not have to plead every legal argument available from those facts. In any event, BT had not demonstrated prejudice or procedural unfairness from the infringement argument becoming clear only at trial.
3. Construction of patent 790. Patent claims state the limits of the monopoly, while the specification describes and illustrates the invention. Limitations should not be imported solely because they appear in embodiments. The claimed profile state transition matrix could address a subset of the possible transitions. It did not have to record every transition available in the system. Estimated data did not have to be profile-specific or recorded data; technical information derived by a rough calculation could suffice. Nor did the claim require every target profile to be examined individually.
4. Infringement of patent 790. BT’s cap-level table identified a plurality of transitions and their priorities. Its safe-rate calculation was estimated operational data. The relevant logic provided sub-rules, threshold tables and an overall rule which collectively determined feasibility. The system therefore infringed claim 1.
5. Construction and infringement of patent 495. “Generating” and “generated” did not exclude selecting pre-stored margin-related parameters through a lookup table. The invention concerned changing parameters in response to analysed current and historical data, rather than the programming method used to obtain them. A narrow construction would also exclude contemplated operation under a technical standard allowing only discrete parameter values. On the broader construction, claim 1 was invalid, but the NGA system satisfied the additional requirements of claim 6.
6. Validity of claim 6. The evidence concerning the prior-art document Kerpez left a material gap between calculating expected performance by reference to a target and determining and sending the claimed parameter set to the modem. BT had therefore not established that claim 6 was obvious.

• Court of Appeal (Civil Division): In [2014] EWCA Civ 1462, dismissed BT’s appeal concerning patent 790 and allowed ASSIA’s appeal concerning patent 495, substituting a finding that claim 6 was infringed.
• High Court, Patents Court: Birss J, in [2013] EWHC 3768 (Pat), held patent 790 valid and infringed. He held patent 495 valid on his construction but not infringed.