Lufthansa Technik AG v Astronics Advanced Electronic Systems & Anor [2026] EWCA Civ 964

The long running dispute between Lufthansa Technik and several suppliers of aircraft in-seat power systems (including Astronics, Safran and Panasonic) has returned to the Court of Appeal, this time raising important questions about how profits from patent infringement should be identified.

The original dispute concerned Lufthansa’s patent for technology used to supply electrical power safely to sockets installed in aircraft seats. The invention included a safety mechanism ensuring that power was supplied only once a passenger’s plug had been properly inserted. At the liability stage, the High Court found the patent valid and infringed, a decision upheld by the Court of Appeal in 2022. The earlier appeal considered how particular wording within the patent should be interpreted and reinforced the principle that patent claims should be read through the eyes of the skilled person and in the context of the invention as a whole.

Following its success, Lufthansa elected to pursue an account of profits, rather than damages. Whilst damages compensate a patentee for losses caused by infringement, an account of profits requires the infringer to give up profits attributable to the infringement. The resulting quantum proceedings reached the Court of Appeal in. A central issue was how to determine which of the defendants’ profits were properly attributable to the patented invention.

Lufthansa argued that Astronics and Panasonic should account for all relevant profits, rather than the 13% awarded at first instance. The Court of Appeal rejected this argument. It held that factual causation alone does not mean that every profit earned from a product containing an infringing feature was derived from that infringement. Where a product contains other commercially valuable features, the court may need to separate the profit attributable to the patented invention from profits generated by other aspects of the product.

The Court confirmed that apportionment will normally be the appropriate approach. Comparing the profits actually made with those that could have been made using a non-infringing alternative may also be useful, but this “differential profits” analysis is a tool rather than a mandatory approach. The judgment also addressed interest. The defendants challenged the award of pre-judgment interest, but the Court of Appeal dismissed the appeal, confirming that simple interest could be awarded from the date the profits accrued.

The decision demonstrates that patent infringement does not automatically entitle a patentee to all profits generated by a product incorporating the patented technology. The court will consider the causal relationship between the infringement and the profits claimed. Where profitability is also attributable to non-infringing features or other commercial factors, apportionment may be appropriate. For patentees considering an account of profits, the key question is therefore not simply how profitable the infringing product was, but what proportion of that profitability can properly be attributed to the patented invention.